I use the antivibration foam made for wrapping receivers in RC airplanes under the GoPro when I put it on the Hoverfly quad. The HiSight mount isn't tall enough to use the GoPro case so it has to ride naked on the platform. A layer of the white foam wrap under the GoPro with a velcro battery strap around it and the platform works well to keep the cam in place and reduce the amount of vibration that makes it through. It's not perfect, there's still a tiny bit of vibes that can be seen in the video occasionally but it works much better than just strapping the camera straight to the platform.
On the Droidworx the GoPro case can be mounted to the Pro Mini paltform using the tripod mounting foot, I sandwich a 1/4 inch thick piece of silicon rubber RC exhaust tubing between the mounting foot and the platform and that seems to soak up the remaining vibes that make it to the mount. Tried the same thing with the Vixia and it didn't seem to help much if at all.
Ken