Is it possible to make a video that's under 1 second long? Or if you try to do that will pretty much every video-making program (or video-playing website) round it up to 1 second?
you can make any length video you want. depending on where it's played, the time counter may have to round up or down to the nearest second, unless their time display can display smaller increments. but that wouldn't change the actual length of the video