As mentioned in the internal topic: I did a quick google on the subject and I found a lot of topics about VU+ not being able to play VC-1 (on several images). So I don't think it's a gstreamer issue, it's simply removed from driver support, apparently.
As betacentauri already mentions, either buy a real media player, or, which in my opinion is a good alternative, re-encode to a current DVB codec like h264 or h265 (I do that often).
It seems like VC-1 isn't much used nowadays anyway. Apparently the closed posture of Microsoft in this area has turned the market against them. Serves them right!
