Before I ask my question, please allow me to mention that I know next to nothing about the technical side of video. I have a DVD with a video_TS folder. Inside the folder are four .VOB files, in addition to which are a few files that appear to handle subtitles. When I shove the DVD into the iMac, the Apple DVD player plays the first .VOB file just fine, but then stops dead. It won't continue on to the next .VOB segments. Does it not perceive that they're there? On the other hand, VLC player has no trouble with the segue from one .VOB segment to the next. So why can the third-party app handle the DVD playback with no problem, but Apple's own DVD player can't?