Why does Flash crash if audio is disabled

I've noticed (in my quest to find out why Flash is dropping frames)

that if you disable the audio in Device Manager, or uninstall the

audio card software driver, Flash will crash playing a video in Youtube.

Isn't Flash capable of playing a video if an audio device is not present on the system?

What kind of design (and I use the term loosely ) has been incorporated

into the Flash Player that it can't handle a missing audio playback device?

This "situation" exists in Firefox running on Windows XP.

Dave