The OmniGroup posted a whole slew of short videos (videolets?) to their site which cover a wide range of topics and skill levels with OmniFocus. Definitely worth checking out.

(There’s a good 2-minute video on Perspectives that you may want to check out if you’re not too savvy with custom perspectives yet. They are, in my opinion, one the best and most-powerful features of OmniFocus on the Mac.)

OmniFocus Videos