By the way, YouTube currently is all over the place. It nofollows links in the Spotlight and Featured areas, where you assume there’s some editorial oversight. But since some of these show on the basis of a commercial relationship, maybe YouTube is being safe. Meanwhile, Videos Being Watched now which is kind of random isn’t blocked — pretty much the entire page is no longer blocked.
Of course, important pages mean nothing to you if they don’t match your query. So, Google combines PageRank with sophisticated text-matching techniques to find pages that are both important and relevant to your search. Google goes far beyond the number of times a term appears on a page and examines all dozens of aspects of the page’s content (and the content of the pages linking to it) to determine if it’s a good match for your query.

Google might see 10 links on a page that has $10 of PageRank to spend. It might notice that 5 of those links are navigational elements that occur a lot throughout the site and decide they should only get 50 cents each. It might decide 5 of those links are in editorial copy and so are worthy of getting more. Maybe 3 of them get $2 each and 2 others get $1.50 each, because of where they appear in the copy, if they’re bolded or any of a number of other factors you don’t disclose.
Fortunately, Google never gave up on the idea of backlinks; it just got better at qualifying them and utilizing other online signals to determine quality from disreputable tactics. Unethical methods can not only hurt your rankings, but can cause your domain to incur penalties from Google. Yes, your domain can be penalized and can even be removed from Google’s index if the offense is serious enough.
9. Troubleshooting and adjustment. In your first few years as a search optimizer, you’ll almost certainly run into the same problems and challenges everyone else does; your rankings will plateau, you’ll find duplicate content on your site, and you’ll probably see significant ranking volatility. You’ll need to know how to diagnose and address these problems if you don’t want them to bring down the effectiveness of your campaign. 

Page Ranks Denver