In the video I demonstrate using a shrinking disc, by removing two dents in a
domed panel.  Once I got the dents shrunk back down (I did NOT use a hammer
and dolly, only the shrinking disc for demonstration purposes), I ran an DA air
sander over the panel to show exactly how smooth of a finish can be achieved.  
You could never tell there used to be dents there.

In normal conditions, you would tap the dents and low areas up with a hammer
and dolly, make a pass with the shrinking disc, and tap up any remaining low
spots before making another pass.  After a few passes your panel with be
smooth, and back to normal surface tension.
On the left is a MPEG Quicktime format, and on the right is a WMV Windows Media Player format.  Depending on which programs
you have installed on your computer, one may be better for you.  If they both start playing, just pause one of them.
Shrinking Disc
Demonstration