YouTube started to test higher quality videos. If you append &fmt=6 to the URL of a YouTube video, you should get better quality videos. Note that this only works for a small number of videos.
Here’s an example of video that’s available both in the regular version (320×240) and in a higher quality encoding (448×336). The audio is now encoded at a sample rate of 44100 Hz, up from 22050 Hz. As you can see in the screenshots below, the right image is clearer and more detailed.
If you append &fmt=18, YouTube downloads the video as a MP4 (H264 with AAC audio), encoded at 480×360. Here’s the same video encoded as MP4.
Related posts:
Posted in 
Tags: 
[...] interesting side-effect of YouTube’s recent push for higher quality videos is that most videos can be downloaded as MP4 files directly from YouTube. Until now, you could only [...]