The response they got was more than they bargained for and certainly now serves their purpose of making the Dems looks bad. Unfortunately, the blurred faces and anonymity about the video raises questions, but they still achieved their goal.
What was inappropriate or unprofessional was approaching the congressman and not introducing themselves, presenting some form of ID (like a letter from their teacher or school ID) and then briefly explaining what their "project" was about. That's how it's done.
In reality, their journalism teacher should have taught them that you should always write or telephone the office first.