% man xorg.conf
Nobody wants to say how this works. Maybe nobody knows ...
After looking it over, I think VideoAdaptor needs to be removed.
Section VideoAdaptor entries have options, identifiers, ports (a subsection which has options), drivers, BusID, and some other things.
Each screen can have 1+ VideoAdaptor declarations (it asks for non-unique strings). In validation, the screen entries are checked against the Section entries. Each monitor now has a pointer to a VideoAdaptor pool entry.
It then goes on that screens are created with xvadaptors for each VideoAdaptor. The actual screens used (not the parser's screens) get that info.
This copying is done so that xf86FindXvOptions can get separate options. The only caller of said function is the glint driver in the pm2_video.c. It's so glint can use like-named options divided into three option tables, instead of using a single option table (with 'input' and 'output' prefixes to names as necessary).
I still want glint's argument parsing fixed regardless.