Why this has no relevance to TWC Internet:
173.194.55.0/24 you are blocking is Google Owned IP Space. This isn't anything TWC would be pushing to you. This is what Youtube/Google sends to you, as it is part of it's CDN Network.
206.111.0.0/16 you are blocking XO Communications owned IP Space.
This has 0 to do with TWC - what it has to do with is how the CDN load balances, and limits connections to Youtube. Youtube also does "JITD" - or Just In Time Video Delivery, which sends small amount of the video each time. This is to prevent people from starting a download and canceling it. They also do Dynamic Bandwidth Shaping on their videos.
I would imagine blocking the IP Space listed has more to do with blocking load balancers, etc... which perform these tasks, which is why you see a more fluid download.