[nine_k]

Hmm. With a video, you can pause it and go google for details.

Asking a professor is likely more efficient. It's still not as easy — you need to break his/her flow, and the professor must have enough spare time to answer.

Also, when you do more yourself you pay less; it can be important.

From my experience, going through harder parts of a textbook with a motivated friend or two works best.

[mannykannot]

The sort of questions I have when trying to do this sort of thing are often not well answered by search engines, as they often of the form "huh? I didn't follow how the last thing you said comes from (or is otherwise related to) the things that came before."