*Duck Hunt: Wonderful surprise, slightly-too-long buildup that made it that much funnier because of it.
Hetalia burger: Bit too specific to having to know the anime I think, but many will get it. Otherwise it was well edited and amusing.
Excel construction: For me, a bit too close to the original. I'm always wary of parodying a parody anime, because it's redundant.
*Hetalia Small World: I loved the first verse. After that it lost a lot of power, but not too much.
Hetalia Happy Meal: Very nice, but I'm nervous some of the softer lines will be lost in the big room.
Tenchi gotta pee: Little long, but the payoff was worth it.
*Death Note explosion: One of my favorites. To be honest, I'm now wondering if this is a contender for an explosion running gag.
*Screw in Tuna: Actually I loved this one, but it starts around 3:10-ish, and should more than likely end at 3:53. After "OH THE HUMANITY!!" when he's flailing. Now here's my problem, the earlier scene choices weren't that good for when he starts losing it and screaming, but some of the later ones felt much stronger for the screaming. I believe not only should this be brought down to that time, but some of the later scenes should be used instead because they're clearer. All in all, very well done.
*L Ring my bell: It's one of those that just needed to be done
4chan meme statements: This was funny in the first shot, the rest weren't anywhere near as good. Cut out all but the first one, the fapping one, and you have a wonderful 'pallet cleanser' clip that can go just about anywhere to bring the energy back up.
Death Note Troll Face: Having seen it before, my initial reaction was a chuckle, but your editing made it that much more solid. Well done ^^ And of course as you said, the music at the end will be taken care of with final editing.
*So fluffy 1: Hell yeah ^^
*Black Butler Troll: Mad credit for this one. I haven't even seen Black Butler at all, and know nothing about it in the slightest, but this is an absolutely excellent standalone involving obviously something that you really should have seen the series for, but definitely works even for people like me. Great job, this will hit a large portion of the audience.
K-on No Underwear: This one COULD be a great one. Certain notes are hit well, but this REALLY needs more time to match the lips to make it work as strongly as it could. As krvabo says, it gets choppy at the end. You should find other footage to hold the note and spend a little more time matching some lip flaps, especially with Mio on her back on the grass, since it's still. The clip will be a major hit if you can spend some more time, but right now the audience becomes aware of the change in footage timing and takes them out of the moment so it ends up drastically lowering the power of the joke.
*Azumanga in room: You've revived Osaka as being fucking perfect as a batshit crazy character. I nostalgia'd all over the place. Thank you for this clip ^^
*Train Charizard: In the middle it slows a bit, after "You can't even throw one of these" but then you salvaged it with the "Thank you for nothing, you useless reptile." Great work. Lots of excellent connective irony between sources.
Chiyo Lazytown: Okay, I love it. But the editing is severely lacking. I know it's a tad tough to lip-sync, and it really depends on what programs you have available to you, but this clip has a major problem in those obvious cuts in the sense that it will cause people to go 'oh, what the hell was that?' when her neck snaps back like she was hit by something. And the lip syncing is a bit lazy (no pun intended), in that I can see you basically grabbed and repeated the same lip flap timing in certain sections without matching. Please take some time to sync it, I'll be happy to help any way I can. Even if you're using Movie Maker, we can help find ways.
Pokemon Electric: Not lol funny for me, but definitely brought a smile to my face ^^ Another good amusing one that will work for a pallet cleanse.
*So Fluffy 2: Caught me off guard, even if it was obvious, because I was distracted by the moans. Good job ^^
Haruhi funky town: Okay, this one has the same problem as the K-on underwear one. It needs more love. Just a couple hours more work at most. You can use footage reversal as your friend here, it'll allow extra lip flaps if you don't overdo it. Right now it's a good clip, the initial reaction is funny, but then it takes me out of it when I see the lips not even close to matching.
*Kung Fu Staring Contest: I love it so much, because I cannot for the life of me tell you if it's too long on the hold or not ^^ If it was shorter I'm sure the payoff wouldn't be as much. Not sure how Kung Fu Panda did it, so this is my first time seeing it. And good use of the audience too, definite brownie points there.
*Haruhi Kay Jeweler: Irony at its best. Thank you.
Mnemonics: Too long. As of right now in its current form, I'd want this one cut. My issue with this one is that the presence of anime in it at all is pointless currently. If you had the male teacher be the narrator, it'd be so much better. Especially when he says "Please come over for gay sex" and when he brings up cocaine and heroin. He does have enough footage to work with to make it work better. Right now you basically just put Osaka there because she's spacy, and the connection is weak, and it's just really slow without some kind of interaction. The clip may do okay, but the audience will be bored rather quickly and this one doesn't offer anything in its current form that will keep them guessing what comes next.
On a boat: Kind of weak. The obvious Noah connection is the only reason it works at all to me. This is another one that not only have we done before, and it was a stronger clip back then, but it's too rare for most anime fans in the audience to get. I'm sorry, but my vote is to cut this one.
Robot Unicorn Attack: Okay, this one is tricky. AMV Hell 4 overdid this joke and it was rather disliked, same with the Halo song usage, so I'd say this one could actually hurt us. Now here's the thing. Because of that, this one is PERFECT to end in an explosion. You even have them running into the star. If we speed up that footage of that section so the audience doesn't catch on too quickly, then this one could be used very easily for an explosion running gag.
Swiper no swipey: Very good.
Can't believe it's not butter: Again, very good, but yeah, audio should be normalized. I can help with that using soundforge if you want.
Shira: I honestly didn't find this one to be that great. The joke landed when she said 'twin sister' and the rest was just there. I'd want this one out personally, since we're flooded with Sailor Moon this year anyway. At the very least shortened, because the joke lands much sooner.
Spider pig: I don't know... the audio may be too quiet to be understood in the room. I couldn't even hear it really, I had to strain, and if you have to strain to get a joke, it doesn't work. Once I got the connection, it was still a bit slow. Honestly I'd just grab the audio from the simpsons of Homer singing it and make the clip only like 10 seconds long and choose a key shot. And don't be afraid to speed up the footage just a bit, but not too much. Otherwise, my vote is to cut it currently.
*Ninja Squirtels: Perfect.
Princess Tutu too sexy: Very good, but I'm on the fence on the length. But I'll trust that the audience will be into it.
*Azumanga cat: Okay... definitely... good ^^
Friends on the other side: Starts exceptionally slow, the ending speeds up. I honestly don't know how to feel about this one. I'm on the fence about leaving it in, but I'll let everyone else decide on this one. I don't know the source, and that means that if you don't know the source in the audience, this one will lose a lot of impact.
*1800Contacts: Easily one of the best ones without a doubt. This one should be given VIP placement, that's for sure.
Insane kid: Hate this song. And because of that... I think it made me like it even more ^^ And with the ending, I liked the "Very good honey" too because it was so ironic. And actually it cleared the negativity of the scene as well, so kept good humor.
*My buddy: Eeeexcellent. Need to know the series to get full impact of course, but the visuals work enough to bring in the majority of the audience.
*SuckySucky5dollah: Fucking perfect. I'm actually not sure I agree the other one should be first, because I guarantee you, after this clip, whatever clip starts next will HAVE to have a slow start, because the audience will be in deafening laughter. And much of it was because we're completely not expecting ANYTHING. This may sound strange, but in order to keep this one as hilarious as it is, I'd even opt out of keeping the longer one. But I like that one as well. I'd put the Friends on the Other Side Sailor Moon clip after this one to pad the slow start.
*Breasts miniatures: Great one.
Gankutsuou jigglypuff: Not too fond of this one. It has no real ironic connection for me. The ending is the best part, but the audio is cut off and it kills it. This one needs to fix that ending at the very least.
Prostitute Hippo: Okay, I think it doesn't feel connected to the other clip because it's a different audio sources. This one is amusing, but I can tell you right now most people will only be half listening because they'll be going "What the fuck is this show?" The other one, however, is UTTERLY HILARIOUS! You have no time to even wonder what is happening, you just lose it because the creature fits perfectly with Cartman's voice.
Paprika babies: I never liked muppet babies, but I was proven wrong about the Fraggle Rock clip last year. This one I can't say much on until I see it in action.
Toys R Us: This one fits a bit better I believe.
Keroro Gunsou Communist: Not a very strong clip in my opinion honestly, lot of still shots, strange fades, and odd timing. My vote is rework or cut it.
*Haruhi Star Trekkin': Another clip that love dearly, but needs work. The lip syncing NEEDS work. It's very spastic to the point that you have trouble following it without the lips to keep you grounded. It starts feeling like just another clip, when in reality the character you're seeing is the one speaking. That's crucial for fast talking clips like these to make sure you prove to the audience a character is speaking. Please spend some more time solidifying the lipsync because this one is one of my favorites.
*Kick ass Chew Bubblegum: Awesome. Especially Sailor Moon's face at the end.
Winter Wonderland Sailor Moon: First time through, wasn't sure. Second time through, love it.
Gundam You're Gay: Not the best clip choices, but the lips work in general. It'll be an amusing clip, probably, but not one I prefer myself.
The rest are mine, so no point in my comment on them ^^