Hi Don,
No, there are not supposed to be ads over the top of the video screen. I just took a look at a couple of the videos using Safari on my iMac and there doesn't seem to be a problem here. What version of OS X and Safari are you currently using?
Also, could you please take a screen shot of the browser window and email it to me? To take a screen shot with your Mac, hold down the command and shift keys, and press the number 4. Your cursor will turn into a crosshair. Drag a selection box around the window and release it. This will save a screen shot to your desktop. You can drag that image into an email and send it to me. The email address is admin@ [this website].
Regards,
Jonathan Atkinson
www.ballroomdancers.com