My gut reaction is that these are pirated, mainly because of the ability to make copies of the manual for distribution to other platforms. An authorized service manual from Yamaha isn't going to cost 21 dollars, even when it's a digital copy (not when the authorized paper manual is about $90.00) and I'd think that any authorized digital copy available to the public would have some sort of DRM protection specifically to prevent someone from purchasing a digital download and making fifty copies for all his buddies. You can't buy the latest bestseller from Amazon as a digital download and then make copies for all your friends. The website specifically mentions that you can burn a copy to a CD, something you'd never be able to do with any typical copyright protected digital media like a manual. I can't imagine Yamaha producing an authorized digital manual that was basically designed to be reproduced and easily pirated. Nowhere on the site does it make the claim that the manuals are authorized by Yamaha, and the covers for the downloads don't match the ones that are on the actual service manual.
I've never heard of any authorized digital service manual for our bike (or any other) that was produced and authorized by Yamaha. I believe that shops have access to digital service manuals, though I don't know if they're the same as the ones that the general public can buy.