According to Sandvine 2007 Internet report, BitTorrent is 52% of upstream and 10% of downstream traffic (in North America). At the time this put it behind Netflix (24% total) but on a par with HTTP (17% total for both) for aggregated net usage.
Whilst I wouldn't argue that all BitTorrent traffic is pirated I wouldn't argue all HTTP traffic isn't either. Somewhere around 17% of internet traffic being used to pirate does seem a reasonable estimate though.
17% is far from being most internet traffic but is indeed a very noticeable amount, which would indeed have an affect on the experience of legitimate users. This idea that piracy is detrimental to the internet experience for other users is one I find interesting and haven't heard mentioned before.
To be fair, he has more than just opinion. He publishes technical books and is the only one in a position to measure the effects of piracy on his business.
He's not going to have big piracy problems, because he was also smart enough to turn SaaS into what is effectively "Books as a Service" (AKA safaribooksonline.com). So he turned a bunch of one time payments for books into a recurring revenue stream that he can use to keep in touch with his audience and which allows him to do things like measuring the demand for new books so he can focus on whatever is hot right now.
In short, anyone who wants to be successful would do well to take notes. He built a publishing business that beats the traditional ones in pretty much every way.
