Tried what? If you mean my solution and the file won't open in Photoshop, then it's fine. Open it with Preview and then save as some other format, if you want.
No problem.
I wound up using that program bc the Mac srcreen caps were disabled when the DVD player was active (at least using the shortcuts). But xl70e3's solution might work as well and will probbly give you a 'cleaner' image if it does (in terms of making sure you're getting the screen edge to edge.