I don't think the 50/25 will fix the YouTube issue. I am having issues with lag on Youtube vids within Xbox Live. It is a joke. Video plays for 5 secs then for almost a minute, spinning (what is that, discs?). And Xbox Live changed channels (Comedy is gone) in YouTube so you have to have You Tube account and customize. Eff that.
CDN (folks running traceroutes on ATT Uverse, and rogers, and Comcast are showing drops somewhere down the line...).
Call me conspiracy theorist but I wouldn't put it past "carriers" that have "content" to throttle You tube somehow (or so many are watching YouTube that "it" needs serious bump in delivery ...
"Ya broke me pipes!" --