Thanks to the anonymous poster who pointed out QT 7.1.6's ability to show individual frame numbers. Using that tip, I wanted to find a way to move the IN and OUT selection markers in Quicktime Player Pro one frame at a time, to allow for more precise edits to be made.
Click once on the IN or OUT point marker that you want to move, and then use the right and left arrow keys, as if you were moving the playhead. The selected marker and the playhead will move together one frame at a time -- use the pop-up in the referenced hint to see the frame numbers change as you do this. To move the IN or OUT marker without first selecting it with a single click, hold Shift down while using the right and left arrow keys. The selection marker closest to the playhead at the time will then snap to, and move along with, the playhead one frame at a time either forward or backward, as you wish.
Or you can move the playhead alone to the precise location you want for your edit, and press I to set the IN point marker, or O for the OUT point marker. Then move it with the Shift technique described above.
These things are simple to do in Final Cut Pro, but I never knew how to do it in QuickTime Player Pro. Until today, that is.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20070516122612157