Maybe you should look at the MP2 and MP4 specifications. Even your 'analog' cable programming was digitized starting in the late '90s so more data could be fed through existing satellites in orbit. It wouldn't necessarily be in the receiver/cable box in your own home, but it would be on the uplink/downlink side where it's sent to and received from the satellite itself.
So yes, nearly everybody has been using Quicktime for about 10 years without even knowing it. The codec has changed now, but the new codec hasn't yet replaced all of the old Quicktime channels.
I never post on here, but this is just a bit too misinforming to let slide. There is nothing "Quicktime" about MPEG-2 or MPEG-4. Quicktime, in its original form, used licensed video codecs from, amongst others, Sorenson. It used H.263 compression technology, which was standardized as a telecommunications standard through ITU-T. Apple was not a part of the standardization process. The current Quicktime uses H.264 compression technology, again standardized by the ITU-T (albeit this time with some - limited - contribution from Apple).
Bottom line: Apple did not invent either video streaming nor video compression. They made it easy to set up your own stream using Quicktime Broadcaster, a program that was unfortunately not used by many and that Apple quietly discontinued without much fanfare.
Quicktime does video compression and used to have applications associated with it for streaming. It wasn't an Apple invention, no matter how much people would like to revise history books in its favor.