But it's being done by professional translators, right? That might be more expensive than having a human do live subtitle transcription, but I bet it's not a huge difference especially relative to the production costs of any broadcast to a large audience, and based on the live subtitles I've seen (mostly on national sports and news broadcasts, so I don't know if that's automated or done by a human) it's hard imagine the quality achieved by professional signers wouldn't be significantly better.