Issue Summary

It is possible to preview video files on Confluence Cloud, in the fabric editor and also on the legacy editor.
Videos with >50MB failed to be previewed where else smaller MP4 videos can be previewed without any issue in the legacy editor.
However, uploading the video on the page and inserting the Multimedia Macro works to preview the same file.

Steps to Reproduce

1. Create a new page in the legacy editor
2. Upload a .mp4 file with 10MB or less on the page for example
3. Upload a .mp4 file with 50MB or more in the same page
4. Insert the multimedia macro and use it to preview the 50MB+ .mp4 file
5. Click on the play/preview for both files and the macro

Expected Results

Both videos will preview the video files uploaded on the page, same goes for the macro.

Actual Results

Only the video .mp4 50MB+ displays the message "Can't preview" and after some minutes "preview is on your way"

Workaround

The same video and also larger .mp4 files (200MB) were uploaded and previewed without any problems on the fabric (new) editor.