In Europe most people don't indicate when approaching the roundabout; only if you're taking the first exit.

Roundabout is basically a straight road that loops itself, so there's no need for blinkers when you're on. You indicate when you want to leave, and that's how cars approaching from your exit know it's safe to get on.

Besides that I'm not surprised Americans don't know how to use them; while nowhere else in the world you'll find a 4-way stop...