I have the Panasonic GX7 and I am planning to buy the 8mm fisheye
If you are going to shoot any video, you need a fisheye. The Panasonic 8mm works great for me.
However for video I prefer the 14-42 power zoom with macro port 35 and inon wet lens it works wonders and has full zoom through
I never liked distorted images for video but may give it a go once I have the lens