A vob file is still an mpeg2 files, and an mpeg2 file is bad news in AE:
Dave's Stock Answer #1:
If the footage you imported into AE is any kind of the following -- footage in an HDV acquisition codec, MPEG1, MPEG2, mp4, m2t, H.261 or H.264 -- you need to convert it to a different codec.
These kinds of footage use temporal, or interframe compression. They have keyframes at regular intervals, containing complete frame information. However, the frames in between do NOT have complete information. Interframe codecs toss out duplicated information.
In order to maintain peak rendering efficiency, AE needs complete information for each and every frame. But because these kinds of footage contain only partial information, AE freaks out, resulting in a wide variety of problems.
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA
Like I said sometimes it works. Just throwin ideas out there. Unfortunately there is really no easy way of importing VOB files, though, it is getting better with Adobe and Avid. I tried opening a VOB with premiere and I could get the video to work fine but the audio did not come in with it. After some research I found some third party programs and could covert the audio to come in but it was a pain to perform.