What DVDs I have with previews (usually ADV, some odd major releases) allow me to skip. Thankfully I haven't run into any wiht manditory previews. Ug, I hate to see that it's a continuing trend, though :| First I had heard about it was Hulk.
I find it's the parts like the FBI warning and the legal disclaimer crap that lock the players so you can't skip, fast forward, or Go to Menu to get by them on a lot of DVDs I have. That annoys the hell out of me. What's the point of ROM medium if I have to sit through crap like that?
I hear Apex players are a good way around this sort of thing as they're lacking software support for fuction locking.