As it turns out, though, they're not always very knowledgable about how deletion works.
I would say that erasing, or attempting to erase, a video of police arresting somebody illegally (How can a journalist be charged with "resisting arrest" when he was not being arrested for anything other than resisting arrest?) is a clear case of destruction of evidence by the officers. Destroying evidence is obstruction of justice. That's illegal. Why haven't these police officers been arrested?"