By its nature, an simple ostinato of two alternating notes is not a repeating single note so RR's don't get activated even though a library might have them. Hence the artificial sound that doesn't sound humanly played. I tried to see if legato ostinato's as featured in the Minority report example sounded convincing on my Dimension Strings and no, because every time it returns to the first note, it picks the same sample out of 3 possible ones.
If Vienna Instruments Pro was smart it would give an option to always randomize or always sequentially use the samples for a particular matrix cell. I would then set that on one of the cells when i wanted to do this kind of thing and it would sound right. If it allowed something like this then each time you return to the first note it would sound slightly different, and therefore have a more realistic legato ostinato feel.
If this feature already exists in VIPro, please oh please someone tell me how to enable it! I would expect it to work especially well in DS since each instrument would have its own random 3 legato samples to pick from out of the RR pool per note.