In general you can trust the audio in the Dutch course, with a few exceptions.
- The g's here are pronounced correctly.
- The intonation of gevangenis is slightly off. Have a look here for a more natural pronunciation: http://www.heardutchhere.net/DutchPronunciation.html#G
I guess it would be correct, however "in de gevangenis zitten" means "to be in prison", people usually don't mean a specific prison, hence not "he is in the prison". If one were referring to a specific prison they would probably say "hij zit in die gevangenis" (that prison) or "hij zit in deze gevangenis" (this prison).
Ah. OK. I'd forgotten about that sense of 'can'. I didn't check where this post was, sorry. At any rate, I think you have to match the register of the original quote. If the Dutch was using a slangy word for prison, then I reckon you could use 'can' but otherwise, they use a formal (foreign) word, you have to use a formal (English) word.