http://www.youtube.com/watch?v=yJAL21IE9fY - Jump to around 1:05, it doesn't get going for a bit after that, but it's hard to get an accurate time stamp on long videos on Youtube.
This is the best demonstration of the size of the earth that I've ever seen.
btw, I would recommend watching the whole speech, but it is over an hour long, so I just linked you to the bit in relevance to the topic.