The video was just the box
Lecture recordings you want to hear on a commute, a concert someone filmed, an interview bound for a transcription tool — the useful part is the audio track sitting inside the MP4. This tool discards the video stream and encodes just the sound as MP3, which every player, phone and transcription service accepts.
Because nothing is uploaded, a two-hour multi-gigabyte lecture starts converting the moment you drop it — the upload time is zero because there is no upload. Several videos queue as a batch.
Your files, not platform links
This works on video files you have. It does not download from YouTube or other platforms — link rippers break platform terms, and this site does not. If the video is on your disk, the audio is one drop away.