I made some pictures of the tempering bath drain stop.

And I also did not see the black chemical reclaiming plate in your video.
Underneath you place 2 liter chemical bottles to collect wasted chemicals.
It looks like

This is my setup in a tiny (3x2 meter) darkroom

Ask Eddie Gunks, he visited last week, the first time he saw an L1200 enlarger from above
My darkroom is in a cellar beneath my house.