If you’re curious to test a site, open a console, and try this:
document.getElementsByTagName("video")[0].videoHeight
You might need to change the 0
to other numbers to find the actual content.
OK I can hate on them all day, but credit where due, they will send video to me in whatever resolution I request: youtube.com 
Not sure how that works with a paid youtube movies subscription.
For the aussies: Shout out to Kayo
(that’s ESPN/Fox/Sky Sports, for upside-down folk). They go all the way up to 4K if the stream does. Almost everything is 1080p. Bit expensive but… you get what you pay for. Nice if you enjoy watching other people touch grass 
I was about to mention stan
, but it’s a good thing I checked, because they’ve joined prime
at 480p and netflix
at 720p to deliver you “HD” movies at 540p. That was 1080p when I checked just weeks ago. <Vader gif>
Apple
are also sucky. IIRC it was 480p. It’s an offence to the movie Greyhound.
Good thread, OP. I am interested if anyone has advice on this… You know, aside from the usual advice lately:

Remember when everyone stopped pirating movies because they could be had for a reasonable price? It was going so well…
Don’t even get me started on bitrate. Or a similar prejudice against firefox, or toward edge. 
Kinda surprised to see Disney on the good side! I’ll be checking them out first thing tomorrow, thanks OP!!
Yeh amazon are down to 480p for movies I paid to purchase in 4K, and could once watch in 1080p at least. Now, I own it and I can’t even watch it, and it wasn’t always this bad, they keep making the browser experience worse over time.
Literally amazon:
Ironically this gif has comparable image quality to buying it on amazon. I hear they have ads now, too. Gross. I just don’t watch there any more.