I applied online. Fast response. They did not pay for the traveling costs. The job interview itself has been performed by one of the CEOs. He did a stress interview. Tried to provoke me during the whole interview ("we are not here to have fun", "I asked you a question, answer it directly!", etc.). In addition, he picked his nose while looking at me (maybe to irritate me). He asked some (silly) questions, see below.
I expected a reject after this job interview. Funnily, they called me 3 times afterwards to offer me a job which I rejected.