The
bandwidth isn't the problem...latency is the problem. Most consumer broadband providers don't give much of a crap about low-latency connections, because when you're watching a static, 5-minute YouTube video, it isn't horrible if it comes with a 500ms delay before play start. It matters a hell of a lot more when the video is live.
Once you're streaming something live and interactively, if nothing else, you're getting boned by the limits of physics: for example, a connection from a datacenter in California has a (current) ~150ms minimum round-trip latency to Europe. That's bordering on a human-perceptible lag, and that's the best case. As I said before, most providers don't give you anywhere near the best case. So you spend a ton of money setting up datacenter and peering arrangements and low-latency interconnects, but you're still in a tough place if your broadcaster is connected to a craptastic residential ISP in New York, and your viewer is in Hong Kong.
Maybe YouTube can do better simply because they're YouTube. But I doubt it. Everything YouTube has done has been to optimize the case of static video delivery, which is a different (and much easier) game. Doing live video at scale requires a different architecture.