Ok 5-6 years of expierience here so I am sorry if this is long.
Clips: Don't throw random clips in the timeline. The timeline is the main thing in your Avatar Music Video, You need to keep it clean and you need to know what you're planning to do on it. To stop things like clips and audio from the episode. Go to library, right click a video, click ''Open in trimmer'' and right click on the audio wave and click what's higlighted in the pic here:
http://img94.imageshack.us/img94/566/0rap.png(I am doing a bigginer clips guide from my expierience, it might help) Now second thing is the most annoying subtitles. Do not panic, you don't need to download some programs etc. (Many people do the mistake and panic and start screaming it has subs lol) anyways got to pan crop of the clip that has subtitles like this:
http://prntscr.com/1vmwrcand than move the box inside, you can move it from any side dw about that. It should look like this:
http://prntscr.com/1vmx0tAlso remember always follow the beats of the song and don't make the clips too long!
(If you want some effects like zooming in and out, blur, beat effect, Linear Blur etc. Pm)?