Youtube takedowns aren't DMCA requests. There is no legal penalty for perjury. It's just a good old fashioned mob shakedown. In this case neither party is even subject to US law so even more irrelevant.
> Matters have now escalated to the point where the game itself has been taken off Steam due to a DMCA request, and the player is “now claiming that they own the rights to the [realistic] game mode”
YouTube has an internal system for handing requests apart of DMCA but videos may also be taken down from YouTube via a DMCA request per law. “Takedown” is a word often used interchangeably for a video taken down via either method.
> Matters have now escalated to the point where the game itself has been taken off Steam due to a DMCA request, and the player is “now claiming that they own the rights to the [realistic] game mode”