It sounds like a cool product. So I suppose you could also do just subtitles?

Maybe the need for voice translations does not emerge that often, because in most cases, if you are interested in a certain field, you either know the language already, or it is really niche. For example IT conference talks - most people would already speak English, even if they are not native speakers.

However, not being a native speaker of English myself, at times I would wish for subtitles because some speakers are hard to understand.

Karaoke is also REALLY big, I should think.