Some releases I've added include an audio CD and a DVD that contains video of some or all of the audio recordings.
While the audio for these two mediums is similar (or identical), I would tend to consider the recordings to be independent: I wouldn't consider two recordings with the same audio but different video identical (e.g. a band producing multiple music videos for a single song), so a recording without video to be identical to one with video (it might make sense to set up a relationship between the two though).
Despite this, I've occasionally seen other editors merge these recordings.
It would be nice if I could mark the recordings from the DVD as containing video, and have the "merge recordings" edit warn on an attempt to merge recordings of conflicting types.
If this flag was added, it would also be nice if new recordings from visual mediums (DVD-Video, Blu-Ray, VHS, etc) had this flag set automatically.