Thanks for reporting this and please accept out apologies for these issues. We have been running some tests here to try to isolate the problem and it looks as though it is related to the non-GrowFX grass patches used in the scene.
The Grass patches are themselves Forest Pack objects with animation randomisation, and it's nesting these inside another Forest Object that's causing the renderer to hang. The other animated objects in the scene should work fine. We're looking into this to see if it's a Forest Pack issue, and meanwhile we'll try to locate an alternative for these grass patches and replace them in the scene. You may also find that baking out the Grass patches to VRay or Alembic Proxies and using these instead solves the problem.
I know it's not much help if you don't have the plugin but just to provide the info, the GrowFX version works correctly, rendering at about 11 minutes per frame using GI Single frame and uses approx 9gb of RAM. This remains steady for subsequent frames. None of us use especially powerful computers and we try to ensure that all our tools and tutorials work on modest hardware. For example the tutorial itself was prepared and recorded on an overclocked i5 with 16gb of RAM and a 560ti.
I hope that helps. I'll keep you updated here soon.