Hello Studio U!

I am here in Udemy more than 2 years I have 4 courses, and almost always when I upload a demo video there is a problem, and I made everything in the properly way as was explained.
Now more than 2 days a have a prob

lem that can't upload my demo video. 

Once I upload the file I receive this picture. Please take a look the picture in the attachment, 
Could You explain me please what's wrong. 
Thank You 
Vinnie Venkov