One thing I want to highlight that she said is that doubles should be called based on the quality of the hit, not the spin of the ball. Just a level 1 ref, but I would say that it looks like in the example video, his intention was clearly to hit with one hand after the other, which is extremely unrealistic in a real game, but would be illegal as he is intentionally completing the hit in two separate actions. I am not sure why she uses the example of receiving with palms when the rulebook states consecutive contcts are only not allowed on finger hits played overhand, meaning theorhetically consecutive palm hits in one action should be allowed. In practice, the rulebook isn't usually followed closely, and almost every finger hit is called a double regardless how clean the touch. If you hit with your palms, then from the angle of the ref it can often look like you are hitting with fingers, so refs sometimes call palms too. I hate that that's how it is, but it makes it much eaier for both the ref and the players to know what to do; no finger hits, and palm hits should be clean. Palm, tomahawk, fist and forearm hits should however theorhetically never be called a double.

I do think that was probably the wrong choice of clip to use as it wasn't a super clear double even in slow-mo. I'm not a very good ref, but I think the "double" they are trying to convey in that clip wasn't that he was making two seperate actions to play at the ball, but that his hands were acting as more than one rebound surface in relation to the ball (ie. it should be fine to play the ball with seperated hands if the inbound/rebound angles remain related to each other, but as soon as you're trying to achieve a rebound angle that wouldn't have been physically possible off a single surface in that play situation, it should be a double).

Just before sets, timouts and subs

@@bisalintensegenius.1457 thanks

Only after an interruption (timeouts, subs, lineup checks, injuries, officials' timeout) and intervals (time between sets).

in theory you could lie down on you stomach, put your feet in the air and then slide all the way across the opponents court as long as you don't interfere with them...