the lock tends to be based on user inactivity. don't think there's anything special about a video.
VLC has an option to disable screensaver during playback, so presumably it mimics some user interaction
Nah, just sets a variable. Any video player should be able to do that, and theoretically a browser could do it too when it detects a video stream, but there are reasons not to (e.g. annoying autoplay video on browser windows you've left open)
the lock tends to be based on user inactivity. don't think there's anything special about a video.
VLC has an option to disable screensaver during playback, so presumably it mimics some user interaction