To stabilise in rotation a 1kg camera, your looking at about 3kg worth of gyro mass (1kg per axis) that's using fancy gyros (carbon fiber/tungsten), probably around 2kg with just a steel disk.

You still haven't done anything about vibration along an axis though. IE up/down blade thump. That's one of the largest vibrations a helicopter sees, as the blade passes over the tail boom/fuselage.
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Mechanical engineers build weapons, civil engineers build targets

Fair enough. I was also looking at a 3-axis gimball. Lets see where that leads to.