Answer
When controls are hidden, tap the video or empty black space to reveal them without pausing. With controls visible, tap that surface to pause or resume. Use Play/Pause directly, or Space when the video surface has keyboard focus. Mute/Unmute restores the previous volume.
Drag the seek bar to choose a time. Playback resumes after dragging only if it was playing before. Controls hide after about three seconds while playing, but remain available during pause, scrubbing, hover, keyboard focus and screen-reader navigation. Mouse movement reveals them on web.
Close, Exit fullscreen or Escape closes the viewer. Desktop Previous/Next arrows move between media. Forward sends the video to a chat; it is not fast-forward. Pinch zoom, annotations and available captions remain supported without enlarging controls.