I find it is possible, with most boats, to empty almost all the water as a swimmer, by just heaving the bow up and letting it flip upright as it comes down.

I do not have video of the process, but I have seen it on youtube before.

I've seen that as well. The video I watched (scramble re-entry) featured:
a) a very fit paddler- not everybody can do a one-hand 'military press' on the front of a kayak, while swimming in rough conditions.
b) an empty boat - not full of camping gear, etc.

I still can't figure out the physics of the 'rescuer' leaning out of/away from his boat, grabbing the bow of the victim boat and lifting that bow to dump the water, without capsizing the rescue boat. Pulling the victim boat on to the rescue boat deck gives an extremely stable configuration, where you can just roll the victim boat inverted and then edge your boat to lift the victim boat. It takes very little arm strength.

Sorry for the OT comments - IMO this is one discussion that should be carried over to the 'Techniques' forum, which gets little traffic.