That's really sad.
Too bad there was no one around with enough skills and courage to jump in and rescue him when he fell.
Damn Cap.
I had a close call there eight years ago when almost the same thing happened to me, but not on that spot. I fell in a bit below the cable pool. Just as I was casting, I lost my footing and next thing I knew I was swimming!
The water was much higher then than what it is now, and the bumpy drift downstream was all but pleasant. I managed to get out of the water by myself at the end of the bend. Scared, freezing but wiser for the experience.
After that episode, I sort of avoided the Cap although it is only a 20 minute drive from my place.
It is a serious river and should be treated as such. And as someone already stated above, those rocks are really slippery.
Be careful out there.