How did you capture? Hope you did not choose FMR (Full Motion Recording), but Automatic?
I did use "full motion" capture.
Too bad, you should know that full motion is mostly not the best choice in Captivate, because not only the filesize is much larger, but editing is a lot more difficult than with the, for CP, more natural capturing mode Automatic (or Custom) where static slides are produced whenever possible and only will be reverted to FMR when necessary.
Between the editing possibilities for FMR you have splitting, which could help you.
Or else, try to view the FMR by using Preview slide (F3 or the play icon on the Timeline, or space bar). Pause on the place where you want to have a pausing. The playhead in CP5.5 will remain on that frame, you can see at which second it is placed. Now insert a button, that will be placed with the start of its timeline at the position of the playhead. If this is really the place where you want to pause, you have to change the timing of that button so that the pausing point is exactly at that place. You can move the button timeline with the mouse, or perhaps better by using shortcut keys: arrow keys (left/right) will move 0,1sec in that direction, CTRL-arrow 1 sec. You can check, edit ths Pause at also in the Timing accordion of the Properties panel of the button.
You will have to insert as action for that button Open URL or File.
I use the FMR "Split" option, and make a still image of the "stop screen", with a button linked inside. Either that, or you can time the button to appear at a certain point in the movie and give the user access to the play controls. The second approach is a little hairy, but adds some technical-looking spiff and an air of intentionality....instructionally, the user will feel more compelled to keep an eye out for interactive moments in a way they aren't used to, but should get used to. Youtube is already flying that car.