Recently Firefox, YouTube and Vimeo made changes in their code causing one of the following issues:
YouTube and Vimeo made a change in its embed code that omits the http: from the scr part of its code. YouTube and Vimeo videos do not appear when previewed on your local computer.
Firefox made a change that prohibits YouTube and Vimeo videos from displaying in websites or learning management systems if part of their code contains http rather than https.
The following steps will allow you to view YouTube and Vimeo videos on your local computer as well as on a website or in a learning management system. (The steps resolve the Firefox issue above as well.)
Use https: - see the steps below.
STEPS for YouTube:
STEPS for Vimeo: