YouTube ALL HTML5 by Klemens Schölhorn

With this add-on you can play all videos on YouTube with your preferred settings (size, quality, playback rate, …) without cookies using only HTML5.

Features

• Automatically change the size of the player and the resolution of the video
• Force HTML5 in cases when YouTube still defaults to Flash
• Start videos paused (always, when not in a playlist, when in a background tab)
• Open video links without the attached playlist (context menu entry)
• Features for users that don't keep cookies:
  • Automatically set volume and playback rate
  • Disable autoplay of recommended videos
  • Hide video annotations

All features of the add-on can be individually configured in the settings (about:addons). These are also directly accessible through a button on every YouTube video page.

Firefox HTML5 video support

You need a current version of Firefox with support for MSE and VP9 or H264. You may have to install ffmpeg on Linux. Without MSE, only 360p and 720p videos are available.

YouTube provides a test site that checks support for the various pieces necessary. If some element is missing, check the following Firefox settings:

• media.mediasource.enabled
• media.mediasource.webm.enabled
• media.mediasource.mp4.enabled