Andromeda, I assume that you missed the ABC special referred to in the OP. The doubts you express about the single-bullet theory were completely put to rest. It's not a theory now -- it's a fact.

Here's what they did, and why it was so convincing. They used the Zapruder film, and other movies shot that day, and did a complete 3-D animation of Dealy Plaza, the buildings and terrain surrounding it, the Presidential limo, and two of its occupants (Kennedy and Connelly). They overlaid the 3-D model directly on top of the frames of the Zapruder film to produce an absolutely exact recreation of the events. Once the animation was done, of course, they could vary the point of view freely. They showed several different views during the TV show, including an Oswald's-eye view.

There were several facts that are often ignored or glossed over by conspiracy theorists. First, Kennedy was not directly behind Connelly in the car; he was six inches to the right (that is, out toward the side of the car) and three inches higher (Connelly was in a jump seat). Second, Connelly was not facing forward at the time of the "single bullet" shot. Oswald missed his first shot; Connelly (and many others) heard it, and he turned sharply to his right, trying to see what had caused the sound. That's the reason the bullet didn't have to change direction in midflight.

In the reconstruction, the animation was frozen at the time the second bullet hit. You could see that its path was absolutely straight, from the 6th-floor window of the book depository, through Kennedy, and then through Connelly. Everything fits, just as it was recorded in the Zapruder film. There's no doubt at all: Kennedy's neck wound and all of Connelly's injuries were produced by one shot, Oswald's second. The first shot missed everything; the third ended Kennedy's life.

As Gerald Posner put it... case closed.