Recently I've been seeing very poor video quality on my Comcast Xfinity setup through my Samsung plasma. I looked all over the web, with most of the folks who were having the same problem assigning it to a "throttling" process at Comcast. While I had no way to really test this, the symptoms matched up: all of the streamed video on my TV was very sharp, with only Amazon video looking like crap. Most people were seeing this problem on Netflix-sourced content as well, while I actually had good quality video but annoying pauses from time to time (this on a 200Mb/sec connection).
Puzzling, since on my desktop I had no video issues with either service. Then I remembered that my desktop's network connection specified 18.104.22.168 for DNS (Comcast's default DNS is 22.214.171.124). Short story - when I changed the TV's "Smarthub" DNS setting from 126.96.36.199 to 188.8.131.52, all my problems went away. Clear 1080p on Amazon, no pauses on Netflix. Switching back to 184.108.40.206 brought the problems back.
Hope this info helps others.
So I guess my question is, does this indicate some sort of throttling from Comcast (either active or passive)?
This problem was caused by Windows, which was created by Microsoft Corporation.