I am not sure I understand, exactly, but how about using:
Code:
v = AssumeFPS(framerate() / 2.0)
a = TimeStretch(tempo=50.0)
AudioDub(v,a)
You will want to play with the TimeStretch parameters (and I am still not sure this will give you the quality you are looking for) but it should do what you want to do, if I understand you correctly.
EDIT: Re-reading your post, it seems I may not not understand at all
But I will leave the snippet above for others who want to use it (or something like it) for the YouTube "trick".