YouTube Has Higher Resolution Videos

Embedded above is a YouTube video that has a resolution of 480×360, up from the standard resolution of 320×240. Someone at the VideoHelp forums figured out that YouTube has started making available higher res versions of its videos, offering 480×360 videos if you append &fmt=18 to the end of a video URL, as well as higher quality audio. The video is MP4 with AAC audio.
Add &fmt=6 and get 448×336 video, with 44100 Hz audio, double the normal. Download time is slower, but with a good internet connection, you won’t notice anything but the higher quality video. If you are embedding the videos and want the higher quality version, add “&ap=%2526fmt%3D18″ after the video URL in both places in the embed code (or “&ap=%2526fmt%3D6″ for the non-MP4 high quality version). Cybernet has a good side-by-side comparison of the old and new image quality.
(via Ionut)

See original post by Nathan Weinberg