Those flamenco players have some intense rasgueado, the really good ones can keep that roll going back and forth indefinitely, like they're doing tremolo on all 6 strings haha. Take it easy on the rasgueado when you're on a steel-string instrument though, it'll scuff up your fingers. I did that a few years back and oddly started getting callouses on the back of my right hand fingers. A bit uncomfortable, thank goodness for moisturizer, but I wouldn't recommend it. Am I the only one this has happened to?