Here's a few things I'm always picking on trailers for:
1. Consistently good quality of film: If you're using footage from battles, try to have them from the same camera - the continuity is important. If the quality is really good on 1 piece of footage and suddenly it's much worse that's marks down for me.
2. The edit: I appreciate trailers that have had editing done to them besides the transitions and the sequencing of footage. If you've done anything to enhance the colour or portray the colour (of your choice) in a really cool fashion then awesome.
3. Music: Please choose music that matches the intensity or the feeling of the bboy/moves you want to show! Half of the reason why trailers are good is because the music puts them in the mood for the video.
4. Angles. This is experimental, find something that works for you.
This is obviously my opinion, but these aren't set in stone - just things I've come to observe.
