How to check video file or not Saving with HTTPPost when I get Request.file

See more:

HTML

C#5.0

MVC5

Dear All,
I want to know How to check video file or not Saving with HTTPPost when I get Request.file.
becoz if some user upload some photo ,I have to save that file.
for example

var file = Request.Files[0];
         file.SaveAs("The path I want to be save);

and then I get that file information from Microsoft.WindowsAPICodePackShell.
so I got the Video Duration from that file that I have been saved.
if i didn't get the Video Duration , I delete the file and return to user that is not support file.
Even I get the information from

file.ContentType

but there are so many how can I ?
I don't want to check the contextType by constant?
for example application/mp4 or sth like.
I don't know how Youtube(Google) handle these things.
if there is anyone help me :-)

Best Regards,
Ko Ko Tun
Developer
B.A English
(+95) 973078722