One thing that is worth mentioning is that Hilde's dad is a journalist and presumably has helped her hone her skills. Which is not to take away anything from her own accomplishments, but merely to point out that she has access to advice and guidance that not every kid journalist is going to have, and so I think she probably knows better than most how to keep out of trouble.
But one thing that is important to note is that while the officer is absolutely incorrect about it being illegal to publish video of a police officer's face when it is recorded in public, he is correct that giving false information to an officer who asks you where you are going -- even if they don't have a good reason for asking and if it would be within your rights to refuse to answer -- can be a crime.
Granted, if you tell a police officer you're going to visit a friend, and then on your way there you notice something worth reporting about and never make it to your friend's house, you probably have a good defense. At the time you spoke to the officer, you had ever intention of going to your friend's house, and so you were speaking truthfully.
But having a good defense doesn't mean that you can't be charged with an offense. Particularly when it involves a small-town cop who seems to be power tripping.