Don't worry about Python 2.x vs 3.x here. Under the hood there's not a great deal of difference in the areas that this course covers. The "dis" module is as useful as ever, all python objects will still be of type (PyObject *), the main execution loop is still there, the concept of frames is relevant still, etc.
The lectures are very interesting and if you have a spare evening it's possible to just blast through the first 3 or 4 without sweating too much.
I watched this series more than once, it has so much details. I believe python-3 is not complete rewrite of python-2. So there must be lot of common code between them. So its useful regardless of its python-2 series or not.
I spent a lot of time reading it while working on the mixed-mode Python debugger for Visual Studio (which, coincidentally, supports both Python 2 and Python 3 - they do really share a lot of things). Much of that work involved parsing and writing internal Python data structures directly, since Python interpreter may be unusable when the current instruction pointer is inside native code (GIL not held, various system locks held etc).
