A shapeflag hitTest takes the form:
if(a.hitTest(x, y, true))
or
if(a.hitTestPoint(x, y, true))
in AS3.
Where a is the Movieclip you're testing against and {x, y} are the coordinates you're testing. The third parameter is the shapeflag parameter. If set to true, you are testing the actual fill of movieclip a, if set to false you are testing if {x, y} lies within the bounding box. It will return true if the point {x, y} is hitting movieclip a.