Why can't I open the video file on my S7?

[AC Question]

I usually edit videos on my computer, upload them to Google Drive, and then download them on my Android device. It's always MP4. For some reason, this video will play in Drive but when I download it to the phone, I get a "No Applications to perform this action" error.
According to what I've read, the fix for that error is in the file extension. So I check the details in the past videos versus the one I m trying to open now and the past file names do end in .mp4 while this one doesn't. Why!? And I don't have the option to rename the file. I didn't t change anything. I use the same software and devices to film, edit, everything.
The only thing I can think of is an issue with the last update (my current version: G930UUEU4APL2/ G930UOYM4APL2/ G930UUEU4APL2... 6.0.1) What can I do?! I need to have those videos on my phone.

 

[nahoku]

Why bother uploading and downloading? Why not just go straight from computer to device or SD?

 

[B. Diddy]

Welcome to Android Central! You can't use My Files or a 3rd party file manager app to rename the file, adding ".mp4" to the end?