I've come across several PC's that will play Flash videos, but with no audio. There appear to be a couple of possible fixes to try, thanks to Selder and others in the Weyland.be blog.

1. Go to Control Panel > Administrative Tools > Services > Windows Audio and make sure the Status is "Started". You will no doubt need administrative access to do this.
2. 1. Go to Start > Run
   2. Type "regedit"
   3. The registry will open.
   4. Go to: HKEY_LOCAL_MACHINE > SOFTWARE > Microsoft > Windows NT > CurrentVersion > Drivers32
   5. Create a new String value named "wavemapper". As value give it "msacm32.drv". (Right click the right window, then select New >String Value from the menu that pops up.
   6. Enter "wavemapper" and it will add that to the list.

      Double-click wavemapper in the list and enter msacam32.drv in the Value Data box.

   7. Close the registry window.