"Disabling autoplay" for silent videos is impossible whenever Javascript is enabled, and it usually is.
What's the difference (to the user) between an animated <canvas> and a silent video ?
What's the difference (to the user) between an animated <canvas> and a silent video ?
Of course, we might be able to find a middle ground between disabling JS entirely and auto-playing all media, but it may be very hard, and that "middle ground" might be changing as website developers find new way to deliver auto-playing media that bypasses the browser's restrictions.