I have the exact same issue on a brand new computer build. But only since I upgraded to 75/35 FiOS service. I found out tonight I need the latest Gen3 Rev I Router -- according to the third Tech I spoke with. They are sending me one in a few days.
I get the burp in audio. It does not occur in the same spot, and sometimes not at all on the same video or audio stream. TV Video on Demand will play flawlessly for awhile -- then suddenly not at all.