Hi @YouveGotMeowxy,
You are missing the required support template. Please fill this form out and edit into your post.
Please fill out the rest of the template since you are missing most of the form.
This will give us the technical info and logs needed to help you! Thanks.
You can also search the forum.
https://help.nextcloud.com/search?q=error%20loading%20video
Example, video player can have trouble with special characters in file names.