On the MKV/vob issue - you might as well know that the file compression is not going to render you a smaller file. In other words, if you're looking to save disk space and you don't want to throw away any other movies, then these two options are not for you. They will chew up about 80% of the capacity required in the original DVD. In most cases, that's upwards of 2 to 3 gig at least. So if you're the type that likes movies to compress down to say under a gig, then you won't want to use these two compression formats. If, OTOH, you're more interested in PQ and you're willing to sacrifice disk space to get it, then you can't go wrong with either of these formats.