Question [Q] Samsung galaxy s4 usb mount (internal)

Hi Gods of the Internet - Please help!

Trying to help out a friend:

He has a Galaxy S4 (I9500) Android 4.3.
He took a video on christmas day - one that he cannot afford to lose, but then deleted it (like a professional noob )
Now he wants to try and restore it.

"Use any recovery software" - they said BUUUUTTTT Can only get the phone to connect in PTP or MTP modes, which cannot be used by the recovery software.

So I put on TWRP for the guy but cannot mount as USB (not sure if this is what that functionality is actually for anyway).

In short, If I can get the phone to connect as a USB mass storage device (Internal SD card NOT EXTERNALSD) then my problem will be solved - anyone know how to fix this?