Cable transmissions are not 'internet video' transmissions. They are different. Your cable tv is a 'video streaming service' too. Xfinity tv is probably a cable communications ie. cable tv, not an internet communication (i.e. streaming tv). It's how you define it to the FCC.
I agree that Comcast is in fact trying to classify this service as a Title VI service. The implementation of this specific service seems to have far more in common with Netflix than standard cable service (even including VoD streams delivered to your STB.)
Whether the FCC considers this as a Title VI service or not is yet to be seen.
Cable transmissions are not 'internet video' transmissions. They are different. Your cable tv is a 'video streaming service' too. Xfinity tv is probably a cable communications ie. cable tv, not an internet communication (i.e. streaming tv). It's how you define it to the FCC.