Sorgrear
Never used MTB, so can't talk about that. I'm a huge fan of the DIT videos. I didn't do too hot on Step 1 because I couldn't absorb the material by just reading FA and doing UW. I used DIT for CK after talking to some of my friends who used DIT for Step 1/2. It helps organize and structure your studying, and teaches you the high-yield information in a very effective, thorough manner. The videos are short, very high quality, and very engaging. If you're a fan of active learning, you will like DIT. I like lectures and learn a lot through them rather than just passively reading a book. Lots of quizzes and stuff to help reinforce the material as you go along, which I really really liked. It's pretty expensive but I think if you're already spending so much money on medical school, why not shell out another chunk to help you get past the boards?
Also, even though DIT is excellent, it's not a substitute for UW. I would definitely supplement whatever you end up using with UW and maybe a good review book.