Maybe it's not entirely strategy. I don't know much about web protocols, but I suppose broadcasting a couple dozen live events to millions of people is much easier and cheaper than making recorded events available, which would require sending each of the million viewers an almost unique package in a given instant. Did I assume correctly, or is sending cloned packages not much harder than sending unique ones?
Multicast is pretty much dead, it doesn't go through consumer routers. So unless your library is large enough that storing it becomes an issue, it really doesn't make any difference.
