How to capture video from another computer?

Question

Video capture

Hello. There is a special computer purchased for old games that do not run on new hardware. I want to record a let's play from it, but, of course, it will not pull the recording software either. Therefore, you need to record from the main computer. How can I do that?
PS The search suggested devices like DKVM-IP1, but the cost of 30k is somehow cool. Something would be cheaper.
PPS Do not offer virtual machines, there are a lot of problems with them, and even if the games start, bugs do not allow you to play normally. Example: in the game Freedom Fighters it is impossible to go down the stairs - the character hangs in the air. On a special old computer, everything is fine, etc.

Answer 1

What about writing video from VGA output?
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