Can't upload a video

It won’t let me upload this video: https://uploads.ungrounded.net/alternate/1146000/1146515_alternate_51726.1080p.mp4
 
For some reason says:
 
“Image can’t be blank  
Image size can’t be blank  
Image width can’t be blank  
Image height can’t be blank  
Image mime type (video/mp4) is invalid  
Image duration can’t be blank  
Image orig sha512 hash can’t be blank”
 
Why is it saying all these things are blank like I’m uploading nothing? It’s clearly a playable video that exists. How do I get it to upload?

@reversalmushroom  
Site doesn’t support mp4, needs to be converted to webm. You can use this site for that.
 
The site will not support mp4 any time soon, including converting from it, as it’s a proprietary format and using it could expose the site to unnecessary legal peril.

Thanks!

@The Smiling Pony
Thanks for this site suggest, I can post videos of episodes I couldn’t when they were uploaded on YouTube.