+1 for this. The chrome extension [1] is even better since it allows for 0.1 playback speed increments, e.g. 1.8x speed, or 2.3x speed.

I've watched some lectures with really slow speakers at 3x and was still able to understand, and really wondered what the people watching the lecture live at 1x must have felt...

[1] https://chrome.google.com/webstore/detail/video-speed-contro...