Flex Slide embedded Video not loading

Hello,
I am trying to create a Flex Slide with embedded video from Youtube.

Under Flex Slides>New Slide>Slide Setting>Slide Video, I add the URL of the video
I create a New Page and choose Flex Slider the one that I made.
When I load the page I can not see the Video Slide at all.

Do I have to enter the link of the embedded video in a specific way?

Thank you for your support
Nikos

ps.By the way Slide Images work perfect