I have Movie Edit Pro 2016 and using windows 10. I just downloaded and activated (i think) the MPEG-4 codec. I have rebooted my PC so theoretically, they should be working.
So I tried to drag a video file (MTS format) to the storyboard and I get a popup telling me "The program needs access to a file with mpeg-4 codec". And do I want to activate it. if I either hit the "activate online" button or "Cancel", I get a message back saying the file cannot be read and the drive or folder is not write protected or full. I know that memory is not an issue. And since I am an admin on my own PC, that isnt an issue too.