Have you looked at commercially available "frame grabbers"
purporting to handle at-speed video, to see
1) which ones produce 24-bit video capture at video rate
2) of those, what's the guts?
Probably a HD or better stream will be difficult to throw
across any distance without heavy compression (another
stage of processing). Where will you put the data, is a
point to ponder. But PAL (as my decades-stale understanding
lies) is low resolution and low frame rate). On the minus
side, PAL and NTSC are pretty poor Z resolution as well,
as they are analog fundamentally and so prone to SNR
degradation from many sources. That being the case, do
you expect true chroma channel ENOB=8?