Bummer.
I came in looking to see if my Sony UBP-X800 would work. Sadly, it appears not to be the case.
Don't give up hope just yet, I believe your X800 uses Linux kernel version 3.10.26, which was only recently found to be compatible with the S6500, and some early production S6700 Sony models.
While to date the above two models are the only known compatible units not running Linux kernel version 2.6.35, that doesn't mean it will always stay that way.
If you have a spare USB thumb drive, perhaps you can add a data point to the research?
All you'd be doing is placing @Nexus3 's ARMinfo script at the root of the thumb drive, and then simply insert it into the X800's USB port. From there if the script is read, it (hopefully) will write two small .txt files to the pen drive which will provide clues about that unit's chipset and Linux kernel version.
Alternatively, if the player does not write anything to the thumb drive, then that unit will likely stay incompatible as evidently AutoScript won't run at all.
On a Mac your pen drive AutoScript folder structure will look like this:
You can fully disregard the "buda" folder, that's something the player will write to the drive for a feature called BD-Live, but is otherwise completely unrelated/irrelevant. After a few seconds, you would remove the thumb drive from the player and put it back into the computer to see if there are now also 2 .txt files with information about the player, if present they will be called kernelinfo.txt, and chipsetinfo.txt, and they might just yield clues that can push in the direction of the X800 someday becoming compatible.
It's worth a try if you have a USB thumb drive handy.