Hi @CharlieGF @Simonclark99 I believe this is intentional. I am testing in-meeting chat, and there are no options to uploading .mov video formats. However, you have the option to upload to an external source such as e.g., Google Drive, Box, etc. So, from in-meeting chat, video upload is not supported

If you've uploading to Zoom Team Chat (differs from in-meeting chat), you have the option to upload camera (picture no video), photo, file (e.g. google drive, box), gif or video message.

If you need to upload a video to Zoom Team Chat, it seems from experience this opens your recents from your Photo Gallery. If you choose photo, in the upper left-hand corner you will have ( < ) button, where you can choose from your video album from your iOS device.
Hope this helps!