Scuba gear supplier scuba.com has a cool selection of instructional videos.
Currently, there are 256 videos, with most of them related to product reviews. When shopping for gear, you may be lucky and find one of your potential purchases reviewed. If nothing else, it's a great way to get a feel for a product when buying online.
It's a useful resource for those times when you just need to see a piece of gear or a process. I plan to reference it from time to time.