That droplet in the video does look like it’s modeled as a soft body, you can even see the characteristic stiffness in how concavity straightens itself out. It’s very possible that they even use Bullet for that (Ammo.js is a cross-compilation of Bullet). So if you go with Ammo, like in the example that @Fyrestar has linked - you will likely extremely similar results. When it comes to caustics - that’s a different ball game all together, and faking it is always awkward, but some basic refractions might give you pleasing looking results. Caustics are just there when you use path tracing renderer, but in rasterizing pipeline, like how most real-time rendering engines work today it’s a very hard problem to solve.