Well ... again ... I know for certain the computer is not actually streaming Xfinity TV ... Meraki just reports it as Xfinity TV. Our ISP is Comcast which is the same as Xfinity so it's not entirely surprising to see Xfinity show up on a Meraki report. What doesn't make sense is that 150+GB shows up. Technically, all of the data being streamed to every computer could be labeled Xfinity (or Xfinity TV) since it is going through Xfinity's network. But why would Meraki be able to single out EA (gaming) and Youtube among others, yet not be able to identify the bulk of the network traffic.
If I were a conspiracy theorist I'd say Comcast/Xfinity is doing something to my data (encapsulating?). So Meraki thinks my actual end communication is with Xfinity ... but it's not. Again, I know for a fact this computer is not streaming movies/tv programs from Xfinity.
I may have to put an agent on the computer itself (fiddler, wireshark) in an attempt to better classify data usage on the client. I don't think I've ever had this problem with Meraki devices at work ... they do a pretty good job of breaking down the datastream. It's only when I installed one at home that it failed to classify the bulk of the data.