The setup utilizes a combination of dynamic IKs and spline IKs.
Have a look at this incredibly smooth watch rig set up by Javier García Munuera, a Co-Founder and Motion Designer at Verso Studio. Created by the Verso Studio team for a promotional video for Hamilton's Khaki Navy Frogman 41 Auto watch, the rig utilizes a combination of dynamic IKs and spline IKs, allowing it to achieve both a natural flow of movement when simulated in an underwater medium and a finer control of the position of the watch in more static shots. According to the creator, the entire rig, including its dynamic joints, was set up in Cinema 4D, a 3D modeling, animation, simulation, and rendering software developed by Maxon.
If you would like to learn more about rigging in Cinema 4D, we also recommend checking out these outstanding tutorials: