Here’s a quick way to find out if a YouTube video has been closed-captioned by a machine (typically pretty bad) or by a person (typically pretty good).
Click the “CC” logo on the bottom of the video.
If the words “English (auto-generated)” appear on the top-left corner, the video has a machine-generated closed-caption.
“English” means the closed-caption is available in English. Some videos contain two or more translations.
Videos that have been captioned by a machine (auto-generated) probably contain errors and omissions.
If the video is closed-captioned by a person, the word “English” will appear on the top-left corner of the video. Someone listened to the video and created the closed-captioning, or corrected the machine-made captioning.
Always check the accuracy of the video’s closed-captioning. Even humans make mistakes.