This question arose from an annoyance while watching twitch streams. I often participate in streams where the streamer is playing a jackbox game. It's quite important to see what's going on on the streamer's screen. My internet connection is quite slow, and so Twitch often buffers. When it resumes, it resumes from the point where it let off.
When TCP Vs. UDP is discussed, the canonical use case for UDP is often teleconferencing, where you don't care if you miss a frame of video, you just want it to be quick. Live video streaming online seems not much different rom that, yet Twitch's video player seems to behave as if it's going over TCP, waiting until it has received enough data to show the next few seconds of video.
So is this what's going on?