If you click on the “English – Automatic Captions” button, YouTube auto-generates caption text.
If you click “Download,” YouTube gives you a file called captions.sbv. This can be opened and edited in Notepad/TextEdit.
You can then listen to the video, editing text for accuracy and capitalization.
Alternately, you can listen and edit the caption text on YouTube, as shown here.
Note: Editing the caption text activates captions to show up by default on the video. If you want to disable this, click the “Disable” button and save your changes.