@Elio glad to see you confirmed "No Issues" on your system.
I have had some similar issues in the past both the course materials and AAP live stream.
After power cycling all associated internet devices, i.e., cable modem, internet modem, WIFI router, all video and audio issues were resolved. That is until the next electrical interruption causes all the above devices to go bonkers again.
As of last evening all was A OK! All except for Griff's suggestion to download the MP4. I looked at multiple areas of the RFFBL course and did not find any reference to MP4. All I see is the Manual, which I have downloaded the PDF with no issues. Is the MP4 only availabel for download if the course is owned and not accessed via My Courses?