I mean, he is alone in a shirt, no suit, no tie, seamingly from his personnal computer (no pro involved, no one else), with an improvised background.
It may be felt as sincere and straightforward, but on the other hand it lacks seriousness and commitment. One would say he didn't care to do something more formal, or even to get someone to help, and just hacked a quick reply before getting home.
I seems more targeted at future investors than to angry customers.
Edit: perhaps I should add that the apologies from groupon japan on the official site where basic style, plain text ones. This is the first video published on the issue, so it's a bit jarring to see something so casual.