Its an epic fight between masterchief, the covenant, and that bitch samus. Seriously i have absolutly no clue how this amazing video was animated. I sort of recognize a few parts in the background as pieces found in a half-life 2 sandbox mod called Garry's mod but even then this seems impossible to be done by anyone other than either a mega cave dwelling nerd or and entire computer studio team.
Excelent video. check it out.