At first I was really impressed with this but after thinking about I realize that the technology already exist.
I already have an app on my phone that will listen in one language then translate to another language the speak it for you in the other language.
The app is from Samsung and is called S translator. Probably only works on new Samsung smart phones. you select the input language then the output language. Press talk then say something. It recognizes speech and converts to text. then translates that text to the written target language. Then press another button and it speaks it in the other language. It works well between English and Chinese.
What this guy has done is to take all the button pushing and selecting out of the app and made it work in real time. I am thinking that the cute little red earbud is simply a bluetooth receiver that receives the audio from the smart phone. Ingenious idea but not groundbreaking technology.