Is there away to bounce visual and audio to an mp4 file once you're happy with something?

Native recording using GEM is not ideal in my experience. I think a good way to do it is using [syphon]. You can download the external for Pd then route the video to Syphon Recorder. Not exactly simple but it works.

How is it done using native gem?

@Fauveboy You can only make QT movies with [pix_record] in auto mode...... without sound.
You would need external software anyway to add the sound you record to the movie file, sync it up, and resample it as mp4.
As @dom1817 says....... it is easier to use some kind of external screen and audio capture program. There is a great one for windows, but osx I don't know.
Syphon will only do the image I think.
David.

A great free solution for video screen recording on every plateform is https://obsproject.com/