I can't imagine it being that big of a project, actually. Somewhere in the MAME code is a routine that converts the vector data into raster data. You just need to hook into that and make frames out of the vectors, then optimize and display them. I'd imagine 1/2 the frames would need to be thrown out because the arcade games probably show more frames/sec than scanners could handle but that's no big deal. I personally have no interest in it, though, since those vector games are only fun to me for about 5 minutes.