- Song that matches the theme / mood / pace / idea / statement of the video. #1 importance. It starts with the song, for me, and radiates outward.
- Interesting idea, insight, concept, or mood. However this is accomplished. I've seen videos with zero special effects that nevertheless did what they set out to do, and that's what I'm looking for.
- Since AVIs tend to lag on my machine (the video lags behind the sound), I prefer MPEGs. Slightly low quality is fine, when it gets to be Quicktime quality, though, that is a bad thing. Even so, I'll watch them for the concept, but I'll be less inclined to keep them unless I REALLY like them.
- When it comes to audio quality, that depends on the song. I can stand a little muffled unless the lyrics are hard to understand or I need to hear subtle sounds in the background in order to understand the video, but that aren't coming through.
Pace depends on your mood or idea, as does music genre and what anime is used.
It all depends on the idea.