Shawn76, the reason is that you are only imbedding a link to the video, and to my knowledge this is the only thing you can do. Without also sending the files and having your recipient save everything to a local folder, etc., the link won't work. We found this out the hard way.
Alternatively, play around with Camtasia (free trial download) or better, because it's a PowerPoint feature, record the presentation in play and then send that file. This is lame - sorry: I haven't actually done the recording in PowerPoint, but I think it might work for you.