I filmed event where "creative" designer used cheap led lights to illuminate the ballroom (hundreds of them) which produced incredible flickering. I tried to use anti flicker filter in my Sony EX1 but it didn't help.
Is there any way I can reduce or minimize flickering in post production. I am using Vegas 10. Thanks in advance for any suggestions.

Well, that'll depend on what kind of "flicker" it is, and how bad it is. If it's the flicker from the LED light cycle, then probably not.

Is there footage you can post?

An idea that I've just got while reading your problem: did you try to superimpose your event on top of itself, using a 50% transparency compositing?

Then, you might shift one track by one frame (1/25sec or 1/29.97) over time: this way, the brightness of the lights would be averaged over time, and you might get rid of flickering.

Actually, the optimal shift should be half the blinking period of the lights. So maybe you would have to unlock the frame-fitting (don't remember the name in English, sorry) of Vegas to accurately adjust the track under the frame duration.

The drawback of this approach is that the video will get fuzzier, but if things are not moving too much, it should not be a big issue.

Hope this helps - never tried it, but it should be quick enough to test.
Frederic