When that happens w/ any 3 PH attachment, you shorten the top link enough to get it unhitched, drag it out of the way and try to back out of the mud using the front bucket to help.
JMHO,
Mike
He also wasn't using his bucket to pull himself out. He should have been trying to push/pull with his bucket at the same time his wheels were spinning.
However, I agree that the rear blade was an anchor - it had to come off.
With that blade on the back, there was no way it was coming out. I've had a tractor stuck more than once with a 16' disc behind. Carry a long chain with you. When stuck, unhook the disc, tractor jumps right out. Chain & pull the disc out, rehook, and back to discing.