the relevant competitors would be cable television, subscription satellite TV services, and various forms of offline media distributing the same content (DVDs at Walmart for example).
I'm not sure how offline competition relates to the "net neutrality" topic in this thread, but any offline competitor necessarily has a physical presence in the state, so it would have been subject to tax for from the beginning.
DVDs at Walmart would be covered by sales tax, as would satellite and cable TV, unless it's a basic subscription.
From Pa. Code § 9.2. Sales and use tax changes:
(2) Pay television. Pay television except for ‘‘minimum pay television’’ is taxable. This includes anything charged to a customer for a service other than minimum pay television service. For example, if a cable television customer purchases basic service and in addition purchases a ‘‘pay’’ channel, tax is owed on the price charged for the ‘‘pay’’ channel. Installation and repair service for pay television with the exception of minimum pay television also is subject to tax.