There's some weirdness around focus going on here, hopefully this comes across as constructive criticism. All of them have the same problem:
When you click on the video itself, the left and right arrow keys work to scrub the video backwards and forwards. Up and down do nothing.
When you click on the scrubber, the left and right arrow keys stop working. Also, the up and down arrow keys start working to rewind/advance the video a different amount of time.
If you click in void space, e.g. on the Winamp example or the blue bar that looks like windows 98 on the Reelplay example - both of these controls stop working, as well as space to play/pause.
Latest chrome on macos.