My first thought was that an unlocking nut would cause it to go outta tune. I guess the guy in the video has his setup really well....like a perfectly cut and polished nut.
The GF video pretty much demonstrates everything that needs to be explained EXCEPT the cavity routing requirements. Some of the slur and slide techniques are the reason why I play fretless more than fretted bass guitar.
The Hybrid X version of the Kahler guitar vibrato bridge features a lockable Allen screw if you decide to lock the bridge into "fixed" mode. By now, there may be a Hybrid X variant for bass guitar.