This is an excellent mod! I am looking through the code and one of the biggest nuggets from it is... how do you get the VirtualBox window to render as a live texture within Minecraft?

What plugin, or where in the code is this happening?

In mcvmcomputers.client.utils.VMRunnable, you can see the code that gets the image. It's actually just taking a screenshot every frame from the VM and putting it into a static variable which then gets uploaded to the GPU by the function "generatePCScreen" in mcvmcomputers.client.ClientMod.