VOB files in a commercial DVD such as Hollywood films are
usually difficult to be a source for this software because of
protection.
It cannot work correctly for a VOB file divided into some chapters.
It is possible to process this type of data by transforming it
using tools for extracting video and audio tracks or for converting
movie format from MPEG-2 to QuickTime.
Please try to search them on the net with keywords
"MacOS, download, demux, mpeg2" and
"MacOS, download, convert, mpeg2, QuickTime."
It might takes more than some minutes to load a movie file
when the playback duration is longer than 20 minutes.