This black car replaces the normal quicktime play/pause timeline that shows up for most mp3/mp4 and other h264 vids. After a little googling I found this solution at the North Arizona University:
If the embedded Quicktime Player plugin does not work in your browser, but only displays a black bar (especially likely if running Windows Vista 64-bit):1. Right click on the browser icon
2. Select properties
3. Go to the compatibility tab
4. Check the box for "Run this program in compatibility mode for:"
5. Make sure it says "Windows XP (Service Pack 2)" in the drop down list.
6. Press "OK" at the bottom