Unsolved Mysteries and Eerie Silhouettes
"However, if your interviewee wants to remain anonymous, perhaps film them in silhouette or change the sound of their voice electronically."
This made me literally laugh out loud because all I could see in my mind was Robert Stack, the host of "Unsolved Mysteries" (Click here if you have no idea what show this is) . Often on the show they would interview eyewitnesses for unsolved crimes and their identities would need to be protected. People's eerie silhouettes and extraterrestrial voices were a regular part of the show.
All jokes aside, it is obviously very important to protect anyone who could be endangered by revealing information. Also, those people are going to make your article all the more real and all the more serious.
I also thought the summary at the end of the page was a handy reminder for how to write a successful investigative article.