check out bandhub – someone starts a song & loads of people can add their playing/video to the song, and you watch/listen to the group playing across several screens.
Someone was trying to get me to sax on it with their guitar last year,
but my pc operating system doesn’t work with bandhub as it is so old, otherwise i would have had a go on it.
the other alternative, is you record/video yourself & then pass it on to someoneelse &get them to add their track to it – bandhub is more easier.
but interested to hear what you have in mind?