That's curious. I have just saved a duplicate copy of the Powerpoint file in Computer B, and have replaced the errant videos by inserting the relevant mp4 files in their place, and that now works. I would have thought that inserting a file, be it a movie file or a jpeg or whatever, means that it is embedded in the presentation.


Also, if what you say is correct, it would mean that it would be impossible to create a powerpoint presentation containing movie files on one computer and show it on a different computer, although in fact, I have for years been doing just that!


When you say that it is a link, what do they link to? If I remove the mp4 files from the folder they were in on computer B, does that mean that they won't work any more in the powerpoint presentation. Also, how is it that even when the movie wouldn't move, the initial picture was there - it's just that it wouldn't move!