A Playing videos dropdown in the toolbar (repeated in the ⋯ menu): Off · Hover · 4 · 8 · 16 · All.
The default is Hover. Out of the box nothing autoplays: the board is a wall of posters and only the card under your cursor plays. There is a short delay before it starts, so cards do not flare up while you sweep the mouse across. Hover does not exist on touch screens, so that mode does nothing there.
All means 16, not all. Literally: the setting resolves to 16. Playing dozens of videos at once saturates the machine's video decoders and freezes most of them. So the 16 cards nearest the centre of the view play, and the rest show a poster. The numeric options (4/8/16) are exact.
Two more conditions:
- a card only plays if it is at least 40 px wide on screen, so zoomed far out slivers do not start;
- the playing set is recomputed about 150 ms after you stop panning or zooming, so nothing thrashes mid-gesture.
Opening the full-screen player pauses the whole board and resumes it on close, so the player and the board do not fight over decoders.
Sound on the board, and only where it makes sense. In Hover mode — the default — the card under your cursor plays with sound. Move off it and it goes quiet again. Every other playing card stays muted, and the numeric modes (4, 8, 16, All) are silent throughout: a dozen clips playing at once with their audio on is noise, not a board.
What it does not do: a card on the board is a looping video with no controls. You cannot scrub, pause or seek on the card — that is what the full-screen player is for.
Something here wrong, or something missing? Tell us — the manual is corrected against the app, not the other way round.