http://www.bungie.net/Online/Halo3UserContentDetails.aspx?h3f ileid=115764562
Step 1.Purchase Bungie Pro.
Step 2. Place desired clips on your profile "File Share"
Step 3. Download clips from fileshare from your Bungie.net profile. Anything on your fileshare will show up at the bottom of there page here:
http://www.bungie.net/Stats/Reach/Default.aspx?player=DutchLe gend%201