Have you noticed that more and more movies and television shows are available in high definition lately? Even radio stations are now available in HD. Of course, you have to have updated televisions and radios to see or hear these better quality works, but there definitely is a difference in clarity.
Where does the high definition footage come from, though? It starts off with the cinematographers who film the pieces. They film the work that is used for the specified piece, and whatever is leftover usually goes unused. It turns out that there are companies out there dedicated to selling the leftover pieces. Through this hd stock, the cinematographers are able to earn extra money with very little extra work.
Being paid twice for one job doesn't sound so bad!