Much of the appeal of YouTube’s new search ad product that launched today is the sheer number of searches that are conducted on the video-sharing site. At the press launch today, product manager Matt Liu called the site “the world’s largest video discovery platform.” Just a small percent of click-throughs on sponsored videos appearing next to search results could have a big impact.

Last month, when word of the search ads product first got out, it was reported there were almost 2.6 billion searches done on secondary Google sites like YouTube in the U.S. in August — beating Yahoo.com’s 2.4 billion — according to comScore. (Google proper, of course, is No. 1 by far.)

So in conjunction with YouTube’s unveiling of the Sponsored Video product — which included Liu highlighting those very numbers on a slide — we checked with comScore to see if “YouTube/other” really does mean YouTube and not all sorts of other products.

“Yes, YouTube is the vast majority of the ‘YouTube/All Other’ we report,” comScore spokesperson Andrew Lipsman told us. But on the flip side, it looks like Yahoo came and claimed back the No. 2 spot in September. The beleaguered portal had 2.5 billion searches in September, compared to YouTube’s 2.4 billion.