Xfinity Stream with Customer Owned Modem

I have my own modem that I’ve provided for internet usage and currently have the 1.2TB bandwidth allotment per month.  In addition, I have the Xfinity Stream app installed on a few smart TVs and devices here at my home.

Can you please confirm that any usage of the Xfinity Stream app in my home does NOT use any of my 1.2TB bandwidth allotment, even with a customer owned modem?