VFX Graph - Flipbook interpolation with a motion vector map: how?

In the 2019.2 release notes it says that VFX Graph got this functionality, but how is that achieved? Does anyone have an example?

We dont have the option to generate motion vector map from within Unity yet. We only have the option to sample an already generated motion vector map for the interpolation. You should use an external software to generate the motion vectors (Houdini can do it for instance).

The fire at the end of the spaceship demo is using motion vector maps as an example.