1200p and above screensaver

So I got this mac pro with Retina 2880x1800 and made some changes so it actually run it at that.

I thought, hmm sweet, let me make some of my own S/S. Lets try to downsample a 4k video into a S/S in quartz?

I did my thing with final cut pro to make it 2880x1800, quartz do its thing to turn it into a screen saver (maybe I have to do extra steps here?)

Save and nothing... Natta.

Ok? Did I screw something up? The 1800 vid works?

So, maybe its this workaround on the 15 inch mbp and 1800 is really not its thing, scale it to 1920 x 1200 (IE scaled mode and not work around to 1800). Run final cut and turn source into 1200. quartz.

Nothing, quartz preview won't go to 1080, at best 720p.

Well ok, moving on, maybe my final cut conversion is broken, let me find a 1080 p video. I found some nice eve online things that looks like a nice S/S (its their promotional stuff, I presumed to be okay for personal use) https://www.youtube.com/watch?v=zF5NnsuQAoc

Downloaded it, import it into quartz and same thing, 720p preview and then when it come time to set the thing, the S/S is just black.

Ok fine, something is up. Try the 720p download instead of 1080p, and bam it worked flawlessly...

I tried google mac max screen saver size or max screen saver resolution, gottten nothing offcial (there are people saying that S/S are limited to 720p, or a certain size so you can have like non 60fps video or like simple videos like animated video with solid colours) so I presume it isn't a system limitation or if there is one it isn't public or well documented (or my cursory 10 second google is bad).

Anyone know what did I break? I would want at least 1080 or 1200 custom screensaver if possible, nvm the 1800 ones...