I just watched the video by Bikeman4u that you posted above, and he was incredibly lucky with that particular crank. I've never had one slip out that easily before. You'll be surprised at the amount of force it takes to dislodge one of these things. My right shoulder and back were a little tight the day after I got this one out (cotters in upper left of pic), and I considered these to be pretty easy:



But again, it was satisfying: