What it does
Some things worth putting on a video layer are not libraries you can link: they run on their own clock, they are made of file-scope globals, and if they fall over they take the host with them. Stagehand is the machinery that sits between one of those and the plugin showing it.
It was extracted from Resodoom, which is GPL-2.0 because it ships a Doom engine. Everything here is written from scratch, knows nothing about Doom and is useful without it, so it keeps the MIT licence the rest of these carry.
Watch it running
Nothing loads from YouTube until you press play.Watch it there instead