Earlier quoted context omitted.
I highly doubt comscore is claiming to be tracking embed/widget traffic. Those numbers are supposed to be for the site itself. They are quantified, and quantcast shows the vast majority of their traffic is to their destination: http://www.quantcast.com/scribd.com see scribd.com vs The Scribd Network
True, so people are linking instead of embedding. But the point is the same... If one person makes the decision to link to scribd instead of the pdf, and 100 people follow that link, it doesn't really mean 100 people value the service.
Source: Scribd says so, according to washingtonpost http://www.washingtonpost.com/wp-dyn/content/article/2008/12...