Well they are connecting their movements even though they aren't connecting physically. If you picture nage as holding something like a jo, some of the movements seem more practical to me. Beyond that, my guess is that these are coordination and responsiveness exercises. I know in my own training, sparse though it's been, it's been stressed that I should have a sense of connection before during and after contact. Perhaps this is one way of building that mental connection. The mention of sympathetic movements in another thread comes to mind. Perhaps the goal is to develop that sympathetic connection of movements. I don't really know though.
If they wanted to train coordination and responsiveness, why not just do it with real technique?
I cant count the number of times i heard a sensei tell a new student "now just take a roll". And ten times out of ten, that student stopped coming back, probably because they werent interested in something theatrical.
Why cant people accept that this is what is happening in these videos, only on a much greater level? I can see the purpose of such techniques as kaiten-nage or tenchi-nage, for example, that arent really effective in a martial sense but are more of a "forging technique".I dont like them, but i can see the point. But these demonstrations are taking that concept into a VERY theatrical area....