The lack of video upload support has mainly be an issue of infrastructure and priorities, not lack of interest. iNat has been growing exponentially for the past few years so we’ve had to spend a lot of time and resources scaling it just to keep up, and video support would be a huge step up in that area. Also, other updates such as improving notifications have taken priority over video support. But when we’ve discussed it, we’ve discussed supporting only short clips so that people would have to edit longer videos. I’d be interested in embedded videos, but then you might have the issue that we had in the past with Flickr, when we loaded photos directly from Flickr rather than hosting them ourselves. If someone took the photo down on Flickr, it would no longer be viewable on iNat. So as supplemental support in a comment that might work, but it would be best to have a photo as well.
I personally really dislike animated GIFs, but I seem to be in the minority, as far as the world is concerned.