TheX650 flight machine is equipped with 3 gyroscopes and 3 accelerometers and it's so stable that it can be flown literally "hands off" the r/c. The ideal tool for high-tech stalkers! 

Google Translated details of the prototypes can be found here (original Chinese version here); there's a bonanza of details, testing reports, pictures etc. 

See here the beautiful camera mount, with the steading mechanism:

 

Lastly, here's a video of another test flight, this time indoor:

 

Thanks to @taweili for the tip.