Here is a guide on how to insert stock footage into documentary or narrative projects, and why you should look for public domain footage.
Using Stock Video Footage
Video editing is an art form in and of itself separated from the video production part. When filming and gathering other footage you are really just preparing the paints for the canvas of your non-linear video editing software. Once you are there you can begin adding things that you could never have produced on your own. Stock footage, which often refers to nondescript footage shot by people other than you, is used in almost every type of production. This is different than using a clip of a known video piece as people will recognize this and it will have to be referenced. News reel footage has its place, but does not fit seamlessly into your project as they are set pieces that also have to be recognized by the film. Stock footage, on the other hand, is usually used incrementally as it does not dominate the narrative, yet will easily fill the gaps and solve images that you could not find on your own.
There are several types of films that you can do. Non-fiction documentary films use stock footage often more often than narrative films. This is done because documentary films often cover a range of real topics and will have to reference different events, areas, or items throughout. These are used to paint a general picture, relate the topics being discussed, and generally provide a visual representation. Documentary filmmakers simply cannot get every piece of actual footage they need so stock footage is used often. Stock footage is nondescript in nature, which means that it is not intended to show a specific event. If it did accurately report a specific event then it could be considered news reel footage. Instead it is supposed to show something similar to what is being discussed so that it is taken smoothly by the audience. For example, if an interview subject is discussing an environmental issue and briefly mentions the possible affects of the animal life in Kenya it is appropriate to use stock footage of animals in Kenya. Stock footage is usually not used to give a visual representation of an actual event. If a very specific robbery is being discussed and stock footage of a similar event is used then this would be dishonest as the audience would automatically assume that the footage being shown was accurate to the situation. Use these stock footage clips mainly as B-roll to cover interview clips and try to keep them topical to what is being discussed. Since documentary films are collages of different types of footage you will not have concern yourself with the fact that this footage may look much different than that of the rest of your film.
Stock footage is used even more seamlessly and easily in narrative films as there are no ethical journalistic concerns at stake. These are often used for exteriors and foreign locations that could not be achieved on your own. If you are going to place the stock footage pieces in you want them to match the visual quality of the other clips in place. This means that if the stock footage you are using is several steps above your video clips in quality it will look out of place. You will often have to degenerate the stock footage clips during the video editing process using video effects such as color correction and video noise. This will have to be fairly slight, so you need to use a very detailed oriented non-linear video editing software like Final Cut Pro.
Public Domain Video Footage
Much of this stock footage you find will be public domain. Public domain usually refers to the fact that the footage you will be using has no copyright protection and can be used for any purpose. Public domain footage is going to be the easiest type of stock footage for you to use in your video editing project, so try to stick as close to that as you can. You can find copyleft and creative commons licenses as well, but they will alter the way you will license your work. If it is not public domain footage you may end up having to pay for the footage and/or credit its author.