All that happened to me after we called the police when we witnessed somebody breaking an ATM machine and driving off with a car was (apart from ID and telling them what we saw) a call a few weeks later from a police officer.

He complained that the firewall at the office would not let him download the video I had uploaded to some 3rd party service and if I could just burn him a CD and bring it. (Seriously.) I talked him into trying some other things, and did not get contacted since. That was weird.

edit: In Germany.