in quite a couple of slides/frames voice slow down like in a lower speed Tape which is not that bad and is understandable still , what makes the watching video a very difficult experience is that the slides (monitor screen) are not quite synchronized with the actual lecture , -in real time- and  makes it hard to understand , although there is an option to go to next slides , it jumps right back to where it think it is supposed to be (Synchronizing itself)