I have a prejudice against instructional videos, partly because when I want to know something, I want to know it right away, and on my terms. For me, it's more satisfying and quicker to flip through a book than to fast-forward through a DVD or videotape. Likewise, on the Internet, I can read faster than video can download and play, at least on my connection and hardware. Don't even get me started on Drupal how-to's--so many of them are video-only, when searchable text would be so much more useful.
However, some things are best demonstrated, not explained. There are amazing free music lesson videos on Youtube, and I've seen some really helpful animations of chemistry concepts. In the interest of being more open-minded, I clicked on the knitting video above, found at Crazy for Cast-Ons, Part 2, which is the follow-up to Crazy for Cast-Ons (Part 1): The Old Norwegian and Some "Tail Tips."
For me, this is a really great video--"Helpful Knitting Tips from Knitting Expert Eunny Jang," on a series called "Knitting Daily TV." It moves quickly, so I don't get impatient, and it's well-produced, so you can see what her hands are doing. I've tried lots of cast-on methods, although I usually revert to the first one I learned, which is, well, idiosyncratic. I do, however, often want a provisional cast-on, so that I can start knitting "in the middle" of a project, and I'm not entirely satisfied with the methods I've been using. I'm excited to try all of these provisional cast-ons.