How can you watch any YouTube video with 4x, 8x or any other custom playback speed you want?
The settings window in the YouTube video player lets you quickly change the default playback speed of your current video. You can get up to 2x the video playback at twice the normal speed. The lower limit is 0,25 which will slow down the video to a quarter of its original speed.
YouTube allows you to play videos at 2x the original speed, but what if you want to speed up and watch videos even faster, say 4x or 10x faster than normal?
Chrome Developer Tools can help there.
In the console click on the clear console
$('video').playbackRate = 10;
If you want to slow down the video, try a value less than 1:
$('video').playbackRate = 0.125;
You can set the playback speed to any value between 0,0625 and 16. This is the allowed media playback range in Chrome.