You cannot add an external mic. If your outdoors try to shield the camera from the wind. You could also try a large paper funnel to funnel the noise to the mic. IMO, the video performance of the FZ-20 is terrible. I would be embarrassed to use it to record someones children.
I suppose if that all that is available, it will capture the moment though.
Minolta X370, 35mm, 50mm; Vivitar 28-80 zoom; Auto Spira-Tel 200mm, 300mm; JC Penney 80-200 zoom;12mm, 20mm, 36mm extension tubes, 2X & 3X teleconverters
Sony Mavica FD-83
FZ-20; 62mm Pemaraal Adapter; TCON-17; Hoya SHMC UV; Kenko Circular Polarizar; Tiffen ND 6, Sky 1-A
Vivitar 2800-D flash; Spiratone Tripod