guitarfan01 said:
I suppose you could go through it frame by frame in photoshop, selecting certain elements and separating them out into layers, then desaturating only the layers you want to.

But that would be quite a job to do. Only take about twenty years.

Of course, maybe that would only be necessary for certain shots.

Or a group of about twenty people could do it in one year (or you could do batch alterations and one person could do it as quickly as their computer speed and storage would allow).