If you're not standing DIRECTLY under the goal post and looking STRAIGHT-UP then there's nothing, zilch, zero, nada - anything that would prove it different... period. Can't be done.
If you're standing just a couple of feet to either side of the post you still would not know for sure.
Okay it's not FOOTBALL, but I played Rugby Union for 7 years and many games are officiated with the two side judges being a player from each team - there's only one center judge.
I can't count how many times I stood under one of the posts to judge a kick, and more than a couple of times I know I would have called it different if I'd been a few feet off to the side, or behind or in front of the goal post, instead of right under it...
No picture on this earth can prove different from what the ref saw. I trust he called it right.... why wouldn't he?? To argue that is ridiculous.
This is a silly thread.... I'm done.