The second to last level you did, at the spiral boxes, the gravity didn't get stronger, the box just had the gravity of the starting box and when it went to boxes with different angels it just seemed stronger because it was pulled to the side more, meaning the gravity didn't get stronger, but it just changed the way the gravity pulled the box.
Oh bye the way if there is a game you can play with people please let me know I want to play with you sorry I text so much like a creep I just like your videos