fjclaus said:
Is stage direction the only difference between a short story, and a TV Script?
Hardly. First, ask yourself how many TV scripts your college prof wrote or even read. Unless she taught at UCLA, USC, or NYU, I'm guessing the number is less than one, so don't put too much weight on her comments. You may or may not have the premise or nucleus for a really good murder mystery, but the pacing of TV relies on much more than "stage directions"--and, BTW, you have to know how to properly use stage directions. Because commercial breaks come at very precise intervals, you have to have your plot points and cliff-hangers at very specific points in your script. And a show like Matlock has a very specific tone and rhythm you would have to be extremely familiar with in order to make your short story applicable. Which leads to:
Second, forget Matlock. Writing specs for any show not produced this millenium is a waste of time. You have to show your chops in current TV shows, so see if your murder mystery can fit in with any of today's shows. Then read actual scripts from that show (places like Drew's Script-o-rama on the web provide free content of a variety of scripts). Then pick up a book or three on how to actually write the TV episode (sitcom or one-hour drama? In your case, obviously, you need to learn the one-hour drama, as each has it's own specific guidelines).
Your short story is 23 pages? If it's double-spaced, 23 pages is actually the length of a lot of sitcom episodes (the other seven minutes are for commercials). Of course, once you transcibe your SS to TV format and indent for dialogue and other such nonsense, your SS will probably double in length. But you still need to reach the 51-53 page mark for a one-hour drama.
Short stories can be morphed into TV scripts. A novel could be turned into a weekly radio program, it's all possible. You just have to learn what the new medium demands, and become as intimate with the new format as possible. Simply adding "stage directions" won't cut it.