Comcast Tony... I posted this earlier but think you might not see it as a response to a previous post of my own.
Comcast Tony, Here is additional information....
I have just returned from a vacation to California and Hawaii. The television playback through the Xfinity portal worked completely... no buffering, no interrupts, clear picture and sound. Using the same computer I returned to New Hampshire and am experiencing the same problems discussed throughout this thread... continuous buffering of live TV, grainy low definition picture and sound. I appears to be something locally and not in the Xfinity portall itself. Hope this helps in your ability to help those of us who would like to stay with Comcast, but are really getting tired of the non-response to a well defined and continuing problem. Thanks.