I used the Xfinity Stream portal on my laptop PC (Dell XPS13) for the first time today. I noticed the lip sync problem on the first program I viewed from my DVR recordings. As suggested, I deleted the show, then recovered it from the "deleted" folder. Afterward, it seemed to play quite good. There may still be a very slight sync issue, but I had to really study it to even see a slight hint of the sync problem. The delete-and-restore solution worked for me on a sample of one show.
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