I've read good reviews about the working climber DVDs and arbormaster training DVDs.
Definitely--once you get through TCC, the Working Climber videos are a great next step.
The guy narrating is really likable and does a great job explaining the techniques. Highly recommended.
Check out the Cornell & Climbing Arborist videos on YouTube too--lots of good info.
Knots--Double/Single Fisherman's, Figure 8, Water Knot, Slip Knot, Prusik, Blake's Hitch, Clove Hitch, Munter Hitch, Alpine Butterfly & Running Bowline are all good to know. Keep a length of rope near the toilet--there's no better place to practice!
Once you buy some basic gear, you'll probably be itching to hike up the first tree possible-- try to resist. Spend a lot of time on the ground or a few feet up until you're VERY comfortable putting what you've read/watched to practical use.
Finally, if you happen to see a tree job in progress, grab some binoculars or better yet, a video camera. It's probably a good idea to ask permission, but you'd be surprised how people react when you take a genuine interest in what they're doing.
Good luck!
Aaron