doing a `curl -v https://redirector.googlevideo.com ` (the host you'll connect to before getting redirected to the actual mp4/m4a streams) opens a tls connection (and gives a cert), but it then hangs for two minutes, before returning a 502. i'd wager some database storing info about the streams crashed :^D (given that it also crashes on /, it's more likely something else)
I remember hearing something like Google Global Cache proxies requests to Google datacenters so that retransmit times, due to last mile issues, are lower since packets do not need to travel all the way to the datacenter. My guess is that they might do HTTP TLS termination there, and when the backend failed to respond in time returned 502.
yep. thinking it over, that makes more sense. amended my comment