Jan Ozer has done some detective work to find out what compression settings You-Tube is using for their HD content. Here’s a summary:

• 720p (1280×720)
• video encoded at 2mbps (.072 bits per pixel)
• h264 High profile with CABAC enabled
• maximum of 3 reference frames, with keyframes every 2 seconds and at scene changes
• 2 B-Frames between each P or I-Frame
• audio encoded in AAC LC at 93kbps, stereo