that is one of my favorite non-linear-editing FXs - but still I don't know haw EXACTLY to make it - i can make the same result with FX SHINE and STARGLOW in ADOBE AFTER EFFECT,or with some other plugin from AE...
In Premiere ,I think,it can be done in parts with a little play with brightess and contrast. Compulsory with key-frame-ing.
From the picture, that looks to me like that saturation was mucked with with, but from your description it may be more complex (a silhouetting effect) Can you link the AMV?
The filters I'd play with are the "Color Corrector" and "Color Corrector 3-Way" in FCP.
I wouldn't take my word as gospel - I'm still just playing with FCP, myself.
Overlay grayscale of original with appropriate brightness/contrast tweaks (to emphasize the areas you want to emphasize) in an additive blending mode, and adjust the alpha appropriately.