What does this icon in Safari mean?

http://i29.tinypic.com/2q1fmag.jpg

What do the little canceled-out play button icons mean? They seem to show up randomly on different websites. What can I do to get rid of them? I've installed a few apps so far, so maybe they are causing it?

I'm a brand-new iphone user, so my apologies if this question sounds silly. If someone can fill me in, or point me in the right direction, I'd appreciate it, thanks!

Message was edited by: h0usehead