Heya - I'll jump in here as I had a chat with the tech fairies, here's how that went:
Sounds like Caren is experiencing an issue specific to her computer and not because of our files, since she is reporting that the test video did not work.
She should check the specific error number of the error she's receiving. She should be able to find this by clicking on the "More Information" or "Web Help" button on the error message when it pops up. There is a list of error numbers up on this page.
There are a number of reasons that it might not be working for her: misconfiguration, missing codec, bad install (might need to fully uninstall and then reinstall), and so on. Tracking down the error number might help shed some light on the specific issue she's running into.
Then he left this on my desk...

...You my friend, I will defend.
And if we change, well I love you anyway.