wrote in message
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I would guess projectors but it may just be a TV trick that the people
there do not see. (like those "first down" lines that pop up in a
football game)

It's a trick.

http://www.sportvision.com/

http://www.sportvision.com/hockey/vi...advertisements

http://www.sportvision.com/pvi-virtual-insertions

I believe it's all done by advanced video overlays. IOW, if you're at the
event in person, you don't see it.

It's a reminder that you can't even believe in things that you can see
anymore. (-:

--
Bobby G.