The same clip four times, once for each way the element can play it. The number on screen is the frame, so what is playing and where it is can both be read rather than guessed.

The browser’s own controls. Nothing starts until somebody starts it.

One control over the picture instead of the browser’s full bar, for a video that is part of the design.

Starts when it arrives and pauses when it leaves. Scroll past it and back: the frame number carries on from where it stopped, rather than a video three screens away decoding frames nobody is looking at.

The scroll is the playhead. Scroll down and the frames go up, scroll back and they go down; stop and it stops. The row is held still while it plays, so the film is not travelling past at the same time. A film meant to be scrubbed has to be encoded with a keyframe on every frame, or the browser decodes from the last keyframe on every tick and the picture stutters. This is the same clip as above, encoded that way.