How did you get the rag through the hose, was it by pushing it through, or by sucking it through using the machine?
It certainly looks like it cleaned a fair amount of crap out of the hose!
Only thing is (and I'm sure that a few here will agree with me), as a PROFESSIONAL carpet cleaner, your solution won't be much good when you've got 15000 feet of vacuum hose, like I have.