Did that in my childhood on wooden stairs in my parents house. Rounded edges, kid of hazardous in general but great to slide down like this. Kind of want to try this again, but I also value the integrity of my bones.
I would like to learn to do it hands free, one foot in front of the other (forward and down to the next step). I can surf a bit without grabbing the rails, but only rarely make it to the bottom. Definitely needs the perfect wooden stairs to get maximum flight time!
It's not dangerous i think though, wooden stairs works best indeed :p