I think I've seen this before, and it looked to me at the time like two people wildly and somewhat randomly striking a target together. I don't know why it's taken me so long to realize this, but this footage seems to be showing a way of practicing sparring without any danger. It looks to me like the stand is being used as a stand-in for your partner, and it looks like Osensei is cutting the stand in response to Saito sensei's cuts, as if he was cutting Saito sensei directly. You can see him shifting angles and trying to preempt a few cuts, and you even see Saito sensei thrust at Osensei at one point. It's like no-contact sparring where you can hit full force and don't have to worry about pulling your cuts. Pretty cool, actually. Or is this generally well known and I am late on the bus?