Why this financial service(?) is using an oompah band for their ad, I don't know. One good thing about posting a YouTube video that's an ad is that you're not likely to get ads on top of it.
The band is Dan Witucki's Heimatland Musikanten. You know he's for real because he's got a HENGEL's concertina. How did I know this? I learned it in a Facebook post from the US Concertina Association!