As a German speaker, spoken Dutch REALLY trips me up because of small pronunciation differences in almost every word. Written Dutch is way closer.

The Dutch seem to understand German better, but my Dutch friends credit that more to education and exposure.

I don't know about the Dutch but apparently the Flemish don't understand German without having learned it at school.

I speak both some German and some Dutch (as nth languages, I can understand them fine but speaking is hit and miss) and sometimes I don't notice which is which and answer in the wrong language, to me they're almost the same language with a different accent. I translate the German into some Frenglish mess for my Flemish friends to help them understand and it works great.

they have access to german tv and watch it.