update to 4o-audio-preview, bugfixes, and commentary

[phundal-openai]

Moved from whisper to 4o-audio-preview, fixed a moviepy import error, and overall small changes in the commentary to go along with model changes. In addition, re-ran the notebook to ensure cell data was updated.

Summary

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Motivation

Why are these changes necessary? How do they improve the cookbook?

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[justonf]

Looks good! Added one suggestion to fix a typo, and one comment about simplifying the flow when using audio-preview