I can see the flex plate move a bit you could place the transmission in neutral and have the wheels off the ground if there is a problem with the Transmission this could help. But if the Transmission shifted ok when the engine went bad then I doubt the transmission or converter got damaged. If you can look at all the rods and make sure that none are broken bent or in the way. Try turning it any way you can to get to the 6 converter bolts. If someone uses a pry bar on a rod journal while some one pushes on the crankshaft nut that could give you extra force. I had a 3.4 that threw a couple of rods I had to disconnect the rod cap and was able to push the piston up into the cylinder to get it out of the way. Maybe doing this with any disconnected rod will help some of the resistance making it so you can turn the crankshaft.
after relooking at the video I see the cast iron web moving so I think the engine is still locked and the Trans is as good as it was when the engine went bad. Again do what you can to get the rods that are disconnected out of the way push the pistons up into the cylinders sometimes the rods get in the way.
You could take the time to remove the cylinder heads it's a few hours more work but that way you can see down the holes to see whats going on. You can take the nuts off any rod you can reach the other one maybe back off what you can just keep an eye that those nuts that are loose don't get in the way.