1. A video processing system comprising: a video input bus, for carrying a stream of video data to the system, a video output bus, for carrying a stream of modified video data from the system, a video processing device comprising a first programmable logic device having an input connecting said first programmable logic device to said video input bus for receiving said stream of video data, a logic configuration within said first programmable logic device to perform one or more operations on said video data to provide a stream of modified video data, and an output connecting said first programmable logic device to said video output bus for transmitting said stream of modified video data, said logic configuration changeable by a second programmable logic device but only at certain times, said first programmable logic device generally configured to operate without any input from the second configurable logic device, and an external control bus, said second programmable logic device connected to said external control bus and connected to said first programmable logic device through an interruptable connection for providing, from time to time, configuration information to said first programmable logic device.