This was never the case with pix_record on OSX and Windows.  The pix_record object on those platforms records actual framerate by timing how long each frame takes to render and compress.  Each frame can have a different length and this is the equivalent of dropping frames during recording.  There is a minimum frame time of 20 Quicktime ticks, which corresponds to 30 fps maximum rate.  A typical pix_snap and pix_record movie will have a variable frame rate which Quicktime apps have no problem playing. 

What pix_record is not suitable for is recording an exact 29.97 DV clip like Final Cut or Avid does.