Ok here are some suggestions :

Do a google search on "google search and tips and tricks"

This is not the most stabe of sites but here's what you do.
World Boxing Video Archive :: log in
1. Sign up.
2. Browse archive and search "documentary"
3. Find a Title that picks your interest.
4. Copy and paste the documentary title on a Google search and click on the "Video" filter tab.
Example: Sugar Ray Robinson - Pound for Pound

All The Best Fights.com: Videos & News on Boxing, MMA, Muay Thai K1 (Has lots of fights; on the sharing board as well)