While learning one of the official courses with videos today, I got all the videos normally the first time when they were shown and maybe once after that, but afterwards it was just grey (no error, just no video and no sound), and the offered answers weren’t clickable, though pressing numbers on the keyboard did work. Pausing and restarting the learning session didn’t help. Now, since only one of the answers offered was from the learning session, it was always easy to answer blindly, but just to let you know… My internet connection seems to be normal on other sites.