There are several ways that you can accomplish this. The choice would be yours.
First, I'd try Video Effects>Adjust>Lighting and look at "spotlight," and "omni."
Next, you could basically use a modification of Curt Wrigley's "Softening Skin Tone" tutorial, and rather than use a Blur, substitute Adjust>Levels.
I did an article on similar at Muvipix. Maybe it will offer you some ideas.
The lighting effect would work well for what you want. The track mattte method would not even be required. In the lighting effect there is a field called "ambient intesity". That adjusts the brightness of the area outside the spotlight. So you can use that do dial down or up the ambient lighting outside the spotlight. You can really use this to make some convincing spotlight effects.
You can also keyframe the location (make the spots move)
If I have not done so already, let me say THANK YOU for that "Skin Tone" tutorial. I have linked to it dozens of times, and have helped many translate the "Gaussian Blur" to all sorts of other Effects. Please never loose that tutorial from your site!
I agree that the Lighting Effect should be able to do all that the OP requested. Keyframing the "spots" can spiff it up quite a bit. I just wanted to give another method to explore.
Thanks for your efforts,
LOL. OK, I'll try not to loose it. Thanks for the kind words.