I've been using YouTube videos. One recommendation -- watch the videos at 2x speed. The information is actually easier to absorb when it's presented quickly.
+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...
In person and by video of the same material experience can be quite different. One of my current lecturers, is very engaging, with great natural flow in the lecture room, but watching via video somehow fails to capture this.
That is for lectures that I miss due to a clash, not re-watching.
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...