I was watching A Very Long Engagement via iTunes on the Apple TV, and was trying to get Siri to disable the second set of subtitles (since it’s a French film, it comes with English subtitles embedded within the film itself and cannot be disabled – but despite this, apparently a separate subtitles track exists and displayed).
This was the result:
I highly recommend going to Settings -> Audio & Video -> Subtitle Language = Off. It’s set to Auto by default. Don’t bother asking Siri, she lies. After the above failure, she eventually understood what I said and told me that subtitles were off. She lied! So I disabled subtitles in the Settings menu and all was well.