Youtube is only overloaded with comcast, not Verizon DSL, question - why?
Youtube (as well as all major geographically dispersed content) controls their global load balancing via source IP address. Since they are in control of where the content is served from, it is very possible that the server you are using is different than someone else at Comcast or the one via VZ.
I'd recommend the basic network troubleshooting and if the issue appears outside of Comcast, contact YouTube support.
Perhaps you should change your title as it is highly inaccurate.