For example i was using Safari, and it didn't work, i changed to Chrome, and i could watch the video with no issues, hope that helps.

Hi Parama can you please tell us wich browser are you using to watch the lesson. Checkout the help center section we have some notes for videos not showing. We recommend using a modern web browser Chrome, FireFox, Safari. Also check if you are watching the videos in a close network, some times companies block some streaming services, try viewing the video in other network to check if this solves the issue.