Cammingo Dos Pro Extra Bold  Vorgeschlagen von deserect 
Lucida Grande  Vorgeschlagen von rjwarda 

It might be this with modifications. its hard to make a good comparison with the small picture

Thanks! That looks really close if it's not. Any idea what a good, free substitute would be?

Lucida Grande is the font. But I know it doesn't look right but you have to put the font in bold-text.

Definitely not Lucida Grande (although I like that font and it comes close). I tried it out and too many letters were off.

I think it's much closer to one of those squarish fonts. Either way I found a few of them for free (Collator, Titillium, Maven Pro), bold them in every way I can, shrink it down to 90% height, and decrease kerning and they look pretty good.