There is also the way the hair seems to move with the muscles of the back, as opposed to being just a suit pulled over an actor. You’ll notice most Hollywood gorillas have really thick hair that seems to hang like a jacket on the actor, which might be a reason why so many ape suits feature shag carpet hair (so thick to hide the fact) or features curly hair (that curly bulk would mask the jacket quality as well). The Patterson beast has relatively shorter hair that allows the camera to see those muscles moving under the hair, so that is another unusual feature when contemplating what could be done as well as what would likely be done.
Would a faker use make-up technology 20 years ahead of it’s time to pull a prank in such a way to ensure the footage would stand the test of time? Or would they be more likely to rent and modify an existing ape costume with the idea of fooling somebody shooting super 8 footage (a very grainy way to shoot that unfortunately doesn’t allow for capturing fine details), without any real thought that the footage would be such we’d still be debating it in 2017? I think the later, that any proposed faker would have just done something that would have fooled people at the time, but that wouldn’t have captured the imagination for so long.
Super 8 in 1967 + a relatively conventional costume = a prank that would last for a decent amount of time, and seems a reasonable thing for prankers to do.
Super 8 in 1967 + an expensive, beyond state of the art makeup that was never used again = a lot of expense for very little payday, and more to hide, and for what purpose. This scenario seems less likely to me, but I can’t rule it out as being impossible, no more than I can rule out that this video is the real deal.