Sure you can do this. Think of it as adding a title or credit sequence, no different at all. instead of the word "My Wedding" your caption will simply say "1" etc

Just create some stills with the number on and alpha channel and drop them on top of your video clip with approrpiate sound effect.

Exactly how you do it will depend on your video editing application of choice.

__________________
I'm not young enough to know everything!