It sounds to me like one of the ISAs is x86/x64 Windows and the other is the thing you get with Direct3D. Sure it's "heterogenous" but only in the same sense as, say, .Net managed and native code both built with Visual Studio are.
I need to watch the video if I'm going to complain any more.
Heterogeneous computing is the idea that to attain the highest efficiency applications should use both of the major processors in the PC: the CPU and GPU. CPUs tend to be best at serial operations with lots of branches and random memory access. GPUs, on the other hand, excel at parallel operations with lots of floating point calculations. The best result is achieved by using a CPU for serial applications and a GPU for parallel applications. Heterogeneous computing is about using the right processor for the right operation.
I need to watch the video if I'm going to complain any more.