What I have read "optimized for Video" means that
the auto focus is:
Internal (no front lens movement)
Accurate (less hunting)
Also the zoomring should be smooth and silent.
For Panasonic this is the 14-140 mm
For Olympus the 14-150 mm and the 40-150 mm
Also the diaphragm blades are mostly 7 and rounded (circulair) to ensure a nice out of focus effect.
Also the long zoom range of the lenses are ideal for Video.