If she were really viewing it in Adobe Reader X, there should be no problem viewing an embedded FLV file.
I did a blog posting about this on InDesignSecrets.com:
In that blog posting, I quote Dave Merchant, Acrobat guru:
If you embed a video file into a PDF page using Acrobat X Pro, the only formats it will permit are Flash or H.264. The resulting object is called a Rich Media Annotation (RMA), and plays using the embedded copy of Flash Player when viewed in Adobe Reader 9+ or Acrobat 9+. It does not use any external software whatsoever, and will play back identically on Windows and Mac. Even if you have the standalone Flash Player installed on your computer, it will not be used. This ensures the highest possible levels of security, and a guaranteed user experience when viewing PDFs with the Adobe Acrobat Family. There is certainly no bias between Windows and Mac; in fact H.264 is so popular precisely because the videos don’t care what platforms they run on.
My hunch is she may really be viewing the file in Apple's Preview application (if it were set up as the default viewer on her computer).
Hi Steve - Thanks for the cogent response. My tester re-downloaded the file
and now has no problems; I'm guessing there was a hiccup in the file