Summary

View File macro in Confluence Server is not showing thumbnail for Video attachment such as MP4.

Steps to Reproduce

1. Edit a page and upload a video attachment via Drag&Drop (for example we use a MP4 file)
2. Insert the video after upload is completed and Save the page
3. The uploaded video will be placed in the page using View File macro

Expected Results

The View File macro should show a thumbnail of the video attachment like in Confluence Cloud

Actual Results

No thumbnail is being shown for the video attachment displayed in View File macro

Workaround

After uploading the video attachment, manually place a Multimedia Macro in the page linked to the video instead of using the default View File macro