The technology is called “self-captioning” and uses complex algorithms.
When the option is enabled, the words appear exactly as subtitles do in movies.
The system was previously available as part of the feature “Voice Search” and some clips of some selected partners also.
Now, Google opens the system for any video that contains audio in English.
The auto-capture started on Thursday, but Google announced that it will take some time until it would “fully processed” millions of YouTube videos in English.
But YouTube wishes that all the users help to expedite the process by creating a button that people can request subtitles, which YouTube will consider as priority.
In the following months, the service will be available for other languages except English.
According to Google, the service is not perfect and it works where there is a clear sound.