The regular parallel dips I do are not like Al's, though. Maybe the way I do it is bad for my joints or something, but I tend to go a lot lower. I try to get my shoulders level with my hands, at least. So far so good, but is that wrong?
Not everyone can handle going that deep on a parallel dip, but people with strong, flexible shoulders should definitely feel free to extend the range of motion. With this type of instructional video, I usually try to stay beginner friendly, hence the shorter ROM. A first timer could be asking for trouble if they go too low, but like yourself, I often do my dips as low as possible. I suppose I could have addressed this in the clip. Hmm...maybe I'll redo it at some point.
"In theory, theory and practice are the same. In practice, they couldn't be more different."
"You can have anything you want, but you can't have everything you want."