Stock footage is footage that is used instead of shooting new footage. You see its use in many movies, like sweeping views of cities and landscapes. You also see this footage when viewing dangerous beasts in their natural habitats, these shots can be extremely expensive so using stock footage opens up the budget a bit. It is easy enough to add in something to stock footage to meet your requirements these days.
A great example of the usages of stock footage is Forrest Gump, how else did Tom Hanks meet historic, and dead figures like John F. Kennedy, Richard Nixon or even John Lennon? There were several historic clips in that movie as well, these are also considered to be ‘stock footage’.
The largest producer of public domain stock footage is the U.S. government. Not everybody can get beautiful pictures of space nebulas or fighter jets in training like the U.S. Military and NASA can. But there are several other sources as well that provide stock footage including public domain, other movies and television programs, news outlets and purpose-shot stock footage.
TV shows like Star Trek which used the same shots of planets, explosions and ships over and over again were able to keep costs way down throughout the five series and ten films. Think about every other long standing TV series, sweeping shots of cities, similar car routes, explosions, common places of venue, etc all of it stock footage.
Online companies like Revostock.com offer stock footage at minimal cost to you starting at $5 or even offer you the opportunity to sell you own stock footage creations. They offer 45-60% royalties, in two different opportunities to the artists. The exclusive contract which means that you the creator may only sell your media for download on Revostock.com, of course you may still sell your footage, music and sound effects for download on your own site and you are also given the opportunity to sell you footage on hard copy (CD or DVD) via other 3rd party sites, just no downloads Doing this contract will earn you 60% royalties.
The non-exclusive allows for downloads and hard copies between Revostock.com and any other 3rd parties. This however will only earn you 45% royalties. The choice is entirely up to you. Either way you earn some great pocket change for your hard work and amazing stock footage.