You need to have yt-dlp installed. It is the tool that will allow you to download the video as an mp3. You should also follow the instructions to set up python for openAI.
Use the command
python3.9 transcript.pyto run the script. It will then prompt you for a url and file name, which you should enter without any extension. Then the script will create a .mp3 and .txt file with the video information.