There are many video formats out there, and not all formats can be played on all devices. The compatibility depends on the installed codecs on the client devices. E.g. a .mov file recorded on an iPhone may not be playable on a Windows PC but can be natively watched in a Safari browser on a Mac.
For maximum compatibility we recommend uploading all videos in the mp4 format which is the most widely supported format.
In the case of Videos for Confluence, the generation of the video thumbnail and preview is carried out by the browser of the user uploading the video. The playback of a video, on the other hand, depends on the system and browser of the user watching the video.
If you are using a video format other than mp4, chances are that the upload may work out fine but that the video cannot be properly watched by your target audience, Please make sure (as far as possible) that your users only use video formats available for all Confluence users in your organization.
We are working on an option to restrict the upload functionality to certain video formats, such as mp4. The feature is already planned for an upcoming release!
Plenty of online tools are available to convert your video from virtually any format to mp4. We can’t endorse a specific platform but searching the Internet e.g. for “convert video online” will yield a lot of results.