I've purchased a bunch of them, but I never felt I got as much out of them as Ryan Bates' Railscasts. For one, peepcodes are too long to sit through in one session and follow along. Secondly, there is a bunch of extraneous stuff in each peepcode that I didn't feel was really useful but I had to sit through to get to the good stuff. Railscasts are seldom more than 10 minutes and I can generally work through them as they play with few pauses.