I believe I've mentioned before about how cinematographers can use smaller, unused clips to still earn extra money. It's really simple. The extra footage can be sold for unlimited use to production companies. The clips are sold "royalty free" so that the production companies can use them as often as they want for as long as they want. In return, the cinematographers receive an upfront payment.
This has become a great way for cinematographers to make extra money on footage that would otherwise be sitting in a HD Stock Video Library going unused. In fact, AlwaysHD has built a business around selling High Definition clips in this manner.
With all the publicity right now surrounding writers wanting more pay in Hollywood, I'm sure that the cinematographers are being affected by the strikes themselves. Selling their extra footage is a great way for them to make a little money on the side to help them through this tough time.