There was a guy last year trying to post a video like this and he used a high speed camera.

When he went to edit the footage, he discovered to his horror that when the board kicked, it nearly sucked his fingers into the blade. Missed by less than an inch. The final edit ended up being mostly a message of "learn from my mistakes". Basically I learned that there's never a good time to have a kickback, even if you're trying to make an educational video.