.mov is just a container format but it's not explicitly disabled in Color.io. The codec might be the limiting factor here - Color.io currently has the same restrictions on video playback as the browser natively. In other words, if you can not open and playback a video file in the browser, you won't be able to work with it in Color.io.

MOV files that are encoded as MP4 are working fine on pretty much all platforms, but MOV files could also be ProRes encoded and that won't work on any platform because the browser does not natively decode it into a playable format.

I'm undecided on how to handle this going forward. It would be possible to transcode most video codecs into a playable format but the performance is terrible. Developing a low-level transcoder that runs smoothly in the browser is not something I can realistically pull off right now and the existing solutions for transcoding client side are not really usable either. In other words, we can only progress as fast as the platform does.