Is the argument for an unmoved mover circular?

I'm Skeptical wrote: 

I realize that classical theists have logical arguments to prove the existence of God. But you don't realize that they all presuppose the existence of God. So yes, they do take God as a brute fact, no matter how much they deny it.


Now, here is presentation of Aristotle's Unmoved Mover. I take it you are implying that this must be a circular argument. How so?