Ok seperate question and I made a smaller video this time

- Hold last frame wont' get you what you want?

- you could pad the wav file (in a sound app) with enough silence to extend it to the length you want.

- you could make a dummy keyframe on some unimportant bone or property at the time you want the action to extend to.

Mark, you really don't need to extend the length of the dialog action.
This might make it easier for you.
Just do the lip sync in the dialog action. Now you don't have to mess with extending its length.
In the chor, make a new Chor action named "Facial".
Do all your facial animation (except lip sync) in this Chor action.
Done.
That's the easiest, most efficient way I've found to deal with these kinds of issues.

Why do you need the dialog action longer? It's only there for the speaking part.
If you're doing facial animation inside the action itself, then just do it and the keyframes you make will set the length of the action.

Thanks guys I think ken suggestion is the way to go or I least I try this way first see were it leads me.

Again thanks