Interesting Auto-Dub feature.
I am French and this is my primary language, but I understand English and Google knows that (it is in my account preferences). So why do I get videos auto-translated from English into French, with a significant loss in quality. It is particularly bad for titles, the translations are terrible and I can't get YouTube to show me the untranslated title. I probably could set YouTube to use English instead of French, but then, I would have French videos translated into English, which is even worse.
And it keeps the auto-translated video title, so if that one is garbage there is extra work involved in figuring out what the original title meant to say, too.
Edit: aha you can switch back to the original audio track