Can you share a model number for the camera module? It may just be talking about a buffer.
The camera can dump information incredibly quickly. Using a buffer allows a picture to be taken right away, and allow the microcontroller to process it be reading it from the buffer.
VGA OV7670 IS the model number from what I can see. I think you're right though about FIFO being somewhere to dump the pictures. Looking on eBay, I've seen exactly the same camera but with a chip on the back & it's advertised as 'with FIFO'. But I've also seen things about wireless FIFO. I'm wondering if I rig up a micro sd card unit that I've got, if I could use THAT as a FIFO?