I don't know the two-handed style enough to be sure but usually for me, not being able to post a shot means I am off-balance at the foul line. It seems to look from your video that you are leaning way to the right and even though you have your right leg extended to the left as a counter-weight, it may not be enough because of too excessive of the body tilt to the right. If, as Impending Doom says, you can get more forward tilt (instead of right) and more knee bend, you should be able to post easier.