:/
I know the basics of a computer, but I can't take one apart, and put it back together. To know something, you have to be able to do it. I can watch Karate for 40 years, and only know what it looks like, but not how to do it.
I know how to spell the word anti-social, and I can spell, and do spell it.
Fourth would not have taught Kakashi how to do it, unless he could.
And besides, if I remember correctly, it isn't a jutsu, it's a nickname. Yellow Flash. Because he is really, really fast.