Hi Molly,
I'm having a similar problem with both importing video narration and with existing embedded video files. When I go through the presentation as a normal PowerPoint slideshow, the embedded files work fine, but when I either preview or publish, the embedded video doesn't work, but the audio of that video comes through fine.
When I import the same video as video narration, the same thing happens. In all the preview windows no video is visible but the audio plays just fine.
Video Specs:
File Format: .avi
File Size: 23.5 MB
Duration: 3:07 min.
Video Size: 384x288 pixels
Frame Rate: 29/sec
Data Rate: 1029 kpbs
Please let me know if you need any other information from me because I'd like to get this figured out sooner than later.
Thanks