From university courses to TED talks, YouTube is a great source of educational lectures. The downside to this unique method of learning is the time it can take up. If you need to watch a bunch of videos in a short amount of time, Reddit user ladyzebra suggests switching to YouTube's HTML5 player and turning the playback speed up.
To enable this, you'll need to activate the HTML5 trial here. This version of the player supports turning up video playback to either 1.5x or 2x the normal pace. Depending on how slowly the speaker talks, you may be able to save up to half the time you'd normally spend watching the video.
I found most videos worked best at 1.5x speed, but there will always be that one person who talks impossibly slow and will benefit from the faster option.