In addition to Video Copilot's free After Effects tutorials, here's a set of free AE tutorials from Mack Dadd Productions. Note that some of these are dated, but many of the techniques still apply; I would think the Video Copilot series is a good starting point, and these could fill in any gaps. A sampling:
- Rotoscoping Tools in After Effects
- Roto-tracking and screen replacement
- Basic 2D tracking
- Basic Expressions
These tutorials are close to an hour long and are available as sizable (and unfortunately slow, in my experience) Quicktime downloads. Note that CS5 ships with a new, very appealing tool for rotoscoping called Rotobrush:
Link: Mack Dadd Visual FX.