I know that there is a media controller capability already but I couldn’t find any details on it.
Anyway, there is some standard APIs by the W3C on this kind of capability:
We can delete this thread if not relevant.
(ActionTiles.com co-founder Terry @ActionTiles; GitHub: @cosmicpuppy)
But this is likely a “compound Capability” of several granular ones, at least divided by type of media.
(I wish SmartThings had a way of defining “Compound or Combo Capabilities”, but Search and I discuss it in a few Topics).