Hi
Just as a point of order, PowerPoint uses the mciplayer to play videos, not
real player or windows media player.
Anyway, the first thing I would check is if it is a file path length issue.
Create a folder on your C drive (e.g. C:\test), move the presentation & the
movie file to the folder then reinsert the video. Does it work now?
I would usually point you to the tutorials on the playsforcertain website,
but they appear to be down at the moment
Lucy