Grabbing "screenshot" from 360 video -> setting it as texture ?

I'm trying to take a still from a 360 video, and then set that still as the texture (cubemap?) of the screen.  At that point the functionality will change, however I am stuck at this point.  I've been trying to use this script (second one down): https://docs.unity3d.com/ScriptReference/Camera.RenderToCubemap.html

I've switched gears and am just going to try a less dynamic implementation to get things rolling.