Nice reverse engineering! Indeed OpenGL is not really a reflection of reality, which sometimes makes it confusing to explain what is going on in natural terms. Without the slab, there is no saying what will end up in that texture. Often you will get views of other applications and other GPU junk. Rule of thumb is just to put a slab in there if you’re going to use capture feedback in OpenGL. In case it’s not clear, the jit.gl.cameras have been carefullly aligned so that they are pointed directly at their associated jit.gl.videoplane. The alpha color of the videoplane will change the trails. Anyways, sorry for causing this tangent. Let’s get back to physics!