Any idea how much bandwidth a Youtube stream requires? Me neither so I recently took some time to have a closer look. Before reading on, take a guess.
Obviously, Youtube does not stream videos in the low compression format in which they are usually uploaded. In a test I did, the 1280x720p video I took with my smartphone had a data rate of about 11 MBit/s and a file size of around 45 megabytes for 32 seconds. Once uploaded and converted by Youtube the HD version of the video (720p) streams at around 2.7 MBit/s and has a total file size of around 11 megabytes. That's the format used by high resolution smartphones today. The default format (480p) version of my test video streams at around 1.2 MBit/s. I've also compared it to other professional content such as movie trailers and the data rates are about the same.
Interesting numbers and the next higher resolution is already in sight, 1280p. As for know, however, that is still rather the exception.
This article on YouTube’s selection of bit-rates (and the effect on quality) is an interesting read:
http://trevorgreenfield.com/rants-and-raves/youtubes-1080p-failure-depends-on-how-you-look-at-it/