The majority of documentaries today use already-createed/stock footage to create something new.
OJ Simpsons: Caught on camera (2014) is a documentary that only uses stock footage that was broadcasted at the time of the case. They offer no academic opinions or the filmmakers constructed interviews. The film only uses the news reel to re-create the event of the Simpson case moment by moment.
I saw this without having much detailed information about the case (and obviously not being born/being a young child at the time of the events.) I thought it was a gripping and interesting way to portray the events that happened. All information that was provided were from US and international media broadcastings, with newsreaders and news reporters giving the audience information as it happened.
This is also interesting to look at, due to the fact that it provides insight to the media usage in the 1990s, were the internet was not as widely used for news events as it is today.