YouTube is testing AI dubbing of videos. AI-assisted automatic translation and voice-over works only for English, Portuguese and Spanish-speaking viewers at the moment.
The author of the original video only needs to agree to dubbing and sometimes correct the result. The algorithm first transcribes the speech from the video and invites the blogger to read the text and make corrections. The result is translated into the desired language and voiced by a synthesized voice.
For the viewer, the choice of an audio track in a non-original language is available in the player settings (Settings → "Audio Track"). You can try it on this video.
Now YouTube is testing a new feature with several hundred bloggers. In the future, it is planned to adjust the accuracy of the algorithm while maintaining intonation and lip synchronization.