The tool works on a basic premise: from 2009 to 2012, iPhones had a "Send to YouTube" button built into the Photos app. Unless you changed the file name, the video title would be the default "IMG_XXXX ...
Add the extension to your Chrome account, then head to YouTube. Navigate to the video with comments you want to search through, and then hit CTRL + S on your PC (or command + S on a Mac ...
When you toggle on captions for a video on YouTube, text will appear in the upper left corner of the video. If the text reads "English (auto-generated)", then that means the captions were created by a ...