
Hi anonymous user,
To narrow down your issue, I want to confirm:
- Are you using .mp4 format? What is the size of this video file?
- Which browser did you use when the issue occurred? Have you tried using other browsers?
- Is there any difference between the two doc libraries?
Per my test, when displaying .mp4 in Edge, it works fine:
When displaying it in Chrome:
Please have a try:
- Download the video and upload again to test if it works fine.
- Create a new Doc Library and upload it.
- Change to another browser.
- Add the Video content type. You could refer to this post.
If the answer is helpful, please click "Accept Answer" and upvote it.
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