Try running PPT as an Administrator and see if that solves the issue.
Hi Jorma, tried running PPT (2013) as Administrator and I get the same error message.
Does the free trial have all the functionality of the paid version?
Yes, the trial is fully functional, just time limited to 30 days.
The next suggestion that Adobe Support would throw out is to try creating a new Admin account on your computer and see if that work better. If you can, I'd give it a try.
You might also try changing the location of the video file and then try re-inserting it. Here is the basis for my suggestions: