This is kind of comical because what Google is doing is even more transparent now.
Microsoft implemented ads that function properly (I played around with the app), yet Google shut them down immediately. I can't help but laugh at this because accessing YouTube videos from the mobile site almost never results in an ad playing, while the YouTube client Microsoft released played an ad prior to almost every video.
Microsoft's marketshare is growing, and it is a legitimate threat to the low-end market. I'm sure everyone has noticed that there are loads of third-party YouTube clients that don't display ads, yet aren't contested by Google - this is a very clear attempt by Google to cripple Windows Phone.