I don't think that live doesn't work with caches. No one watching live would care about a O(s) delay, which is highly amenable to caching at ISPs and streaming

I don't think that live doesn't work with caches. No one watching live would care about a O(s) delay, which is highly amenable to caching at ISPs and streaming changes from there to downstream clients. Offhand I'd say that would support O(ms) delay but no less.