One solution is to duplicate your footage twice, apply find edges to one layer and use it as a luma matte for a blurred copy of the footage.
Another, much more complicated technique that I've used for stills. You'd need to adapt it a bit for video. (from the colortheory group, IIRC.)
1) Make four identical layers. Layer 1 remains untouched.
2) On Layer 2, Gaussian blur, Radius 2.0 (for starters, may adjust).
3) Having blurred Layer 2, apply a curve that lightens the midtone very slightly.
4) Change layering mode on Layer 2 to Darken. This will disallow most of the layer because of Step 3, and will only fill in small white blotches.
5) On Layer 3, apply Gaussian blur at double the radius of Step 2. (Reason: darker spots on the skin tend to be larger than white spots).
6) Having blurred Layer 3, apply a curve that darkens the midtone very slightly.
7) Change layering mode on Layer three to Lighten. This will disallow most of the layer because of Step 6, and will only correct age spots and other dark blemishes.
8) Compare Layer 3 to Layer 4 (an untouched original) and merge the two as desired with a layer mask.
