[lumost]

I don't know anything about google internals, but in many other applications the search engine is optimized on long-term engagement and profit data. I wouldn't be surprised if it turned out google optimized page rankings based on the profit google earns from it's ad business on the page.

[tomatofrank]

The evidence supporting this is the 4 YouTube videos at the top of the list, followed by 3 of those 4 YouTube videos on page 2 (LOL).