[bgia]

How do they do it? Do they cheat and have a video for every minute of the half-day? Or is it actually a CGI rendering of the watch ?

[CheezeIt]

The one with the time and running chronograph has drop shadows on the subdial hands and some reflections of the chrono seconds register off the dial, but no reflection of the chrono seconds off the hour and minute hands.

[Chyzwar]

The first watch on the landing page is video used as background with autoplay.

The second watch is Canvas on top picture. Once picture and canvas loaded, it animates time change on canvas.

Not all watches have precise time.