They are great for learning from square one on a topic if you don't understand something. But I agree with the above: too slow and detailed for Step 1 prep.
For example, he spends about 8 hours talking about carcinogenesis. That's 8 hours of explaining cell signalling pathways, proto-oncogenes vs. tumor suppressor genes, and finally explains some of the specific mechanisms involved with conditions like Li Fraumeni, Retinoblastoma, APC, HNPCC, etc.
So if you like having stuff fully explained to you, $99 is probably well worth it. If you're more of an independent learner and do well with powerpoints, textbooks, and Step 1 prep materials I'd go without.