Zebra is not a "warning" of "overexposed" areas, but rather a guide to show you parts of your frame that will be pure white or close to it. Pure white means there is no detail in that area and you will never be able to get it back in post.
With the limited latitude of video, you want vertain areas to be zebra'ed- lights, areas of a white shirt, shiny objects, a white wall etc.
Always expose for your subject, regardless of the background (or foreground).