Yes, when I learned the hard way that sport fighting is not the same as self-defense. That was in a fight that I almost lost. The only thing that kept me from losing that fight wasn't my ability to fight but my ability to keep my distance and prevent him form getting with in range to strike me. (aka run away).
There is also an air of malice that comes with street fights that isn't present in a sports fight. I can fight in 100's of professional UFC fights and never get the same fear and urgency that comes with being in a self-defense situation. I don't care how bad ground in pound is in the ring it's never has the same malice and fear that it has when it's done in the street.
I've done sports fighting, just not on a professional level. With sports I don't get the same concern about my existence because I know there is a ref there. I know if I have had more than I can take, I can quit and the fight will be over. I know at the end, the guy that I'm fighting with will probably say "Good fight." I haven't had one that didn't say it, win or lose. I know that if I need medical attention that someone will be there to give it. I know there are rules that have to be followed during a sports fighting. I know that there are no ambushes or dark corners in MMA. I know that the rules were put there for the safety of the fighters. This means that even as brutal as professional MMA is, it can get worse, and on the streets it often does.
I didn't post the videos so that you would take their word. I posted the videos so that you could see a different perspective from people who do sports fighting and how they felt about self-defense.
On a personal level I don't care if you accept any of what is being said or shown, because I know without a doubt that self-defense is one of the topics where people either understand or learn the hard way about self-defense.