User blog comment:BladeFrenzy/Help with video quality plz?/@comment-3184423-20110302091441/@comment-1906486-20110303165458

Most likely more space, never really checked 100% on it though. It just offers a smoother recording time, YouTube HD works 100% fine to me really. Just I did my Desert Fox runs with it, after finding the other codec works better I used that instead.

It's not better IMO as it would be, just less lag put on the recording. Also don't forget if you set it to HD, the game before the bug fixes would reset to YouTube Standard Quality. Many people complained HD had no quality, but it's being that bug reverts all your settings to default.