Do you mean the timed ad pages that pop up before you get to the download page?
I don't see those with Firefox but are extremely annoying with IE, especially waiting for the "skip ad" button to appear so I can get past it... >_<
Personally I hate them, but (I think) they pay more than regular ads so I can see why SCG has these types of ads. I do think they occur way too frequent when trying to browse the site, an ad every one to two page clicks is really off-putting.