Unfortunately, the forum is probably your best bet at the moment -- new features are coming out at a higher rate than polished documentation for those features, though maybe the documentation people are about to drop some goodies in our laps and we just don't know about it yet.
Specific questions usually get answered pretty quickly here, so long as the answer doesn't require knowledge that only an Omni employee would have. A bit of feedback with Help->Send Feedback or email to
omnifocus@omnigroup.com asking for more up-to-date documentation and videos wouldn't be a bad idea, either. The release notes are compactly written, but contain a lot of information, and I refer to them periodically, often learning something new on each reading.