Android: DVD playback
It is only possible to open individual VOB files. It is not possible to open a folder as a DVD. This is in fact very useful on Android tablets even though the tablet doesn't have a physical DVD. When I travel I often rip DVDs to vob files and put them on an SD card (on a netbook, since I can't get this to work on a tablet).
Also, in this connection, there doesn't seem to be a way to set the audio track or subtitle track on-the-fly (very useful for DVDs). And deinterlacing seems to be nonexistent.