SONY P100 in Video Mode

I have not taken much mpeg video with my P100, but am finding that the
brightness varies significantly from high to low or vice versa when
someone walks into the frame.

Are there certain mode selection settings that should be
disabled/enabled when taken video clips? Such as MAF being on in
Still camera mode. Does that have an ill effect on the movie mode
brightness changing so drastically ?

Thanks for any info; and I will again refer to the Operator's Manual!


Vince
On Long Island, NY