Only 360p on Youtube with HTML5

Solution 1:

Ok, a friend was also experiencing the same issue and this apparently helped:

1. Go to https://www.youtube.com/html5

2. Ensure MSE i.e. Media Source Extensions (required for MPEG-DASH i.e. adaptive streaming) and H.264/WebM are supported by your browser (^† see below for more). Also if you right click any video and select Stats for nerds you can see whether DASH is supported or not:

   

3. Click the Request the HTML5 player button:

   

4. Now you should see this and can try viewing videos at resolutions above 360p:

   

^† To enable MSE in Firefox go to about:config and ensure all of the following are set to True:

media.mediasource.enabled
media.mediasource.youtubeonly
media.mediasource.mp4.enabled
media.mediasource.webm.enabled
media.fragmented-mp4.exposed
media.fragmented-mp4.ffmpeg.enabled

(Actually even if either MP4 or WEBM is enabled that should suffice, but if one doesn't work try enabling the other.)