millions of americans are now use go-pro cameras giving those of us in the news business amazing pictures. for go-pro founder it s money in the bank. his net worth is now nearly $4 billion. here s david muir who met with him to take it all in. reporter: the corner of fifth avenue and west 33rd street in new york. hi, guys. reporter: while they are waiting for us with their own cameras. the inventor of the go-pro. right there with a camera for me and a camera for him. we begin our walk through the empire state building. we meet cesar, part of the security team. you can see the small go-pro he s carrying an what they call an extender. a man-made arm. this is the first time he s tested out his cameras at the empire state building. nick woodman came up with the idea. just 26. he s a surfer.