Cacophony of issues (and please pardon, I am a technical dumbass):
File sizes for reference:

I have all but given up on the larger file and am trying the three smaller files I've made by chopping the large one to bits.
Here's what Chrome's giving me if I try to load media directly into my post:

If I attempt to attach the file, it goes through its progress bar until about 45%, then just gives up and hands me the following:

Tor froze at 31% (and seconds after I took this screenshot, gave me the same result as Chrome. It's been doing this repeatedly, behaving like a slower Chrome with the same results from attempted uploads)

I've gotten so desperate I've actually opened up freaking Safari, of all browsers.
Which I've finally gotten some progress with - each file loads to about 70% and then freezes, but if I do this 3-4 times in a row it'll finally go through.
As you can see, images are doing fine, but .mp4's have been highly problematic.
Dunno if it helps, but here's the machine I'm running:
I've FINALLY gotten my files loaded after an hour of fucking around and having to go to Safari of all browsers, so I suppose I no longer need assistance, but figured I'd post this update anyway because the site's being a lot more bitchy than normal on my end.