I use impresspage 4 -current verion I send the video to the repository. I add a text widget to the page. I click the Insert / edit your movie and choose the video from the repository. Unfortunately, the movie does not appear. If I add the html widget and I will add the video in the video tag, it works.
Is this a bug?
You are probably using a non standard text widget, but one provided as a plugin. Because default widget has no video capabilities.
The plugin may have limited capabilities. I suggest you to use Video widget to display videos from YouTube or Vimeo.
Alternatively you can use HTML widget to display your video in some unique way, like html5 video player, etc.