If the banging is loudest in 1st and Reverse it sounds to me like a broken/chipped tooth on the 1st gear. If it was the throwout bearing the noise would be consistent throughout the gear changes. When you push the clutch in it is relieving any load on the transmission gear sets. I would drain the transmission and look for chunks or take off the side cover and inspect the gears. Do it soon so you don't tear up any more gears.
SimS
