Currently, we don't support preview for direct links to video files, however we do have this on our roadmap.
At this time you can embed videos from popular websites such as YouTube, Vimeo, Wistia, Vidyard, Facebook Video, etc. We also support most services that support oembed standard.
Do you have a non direct link to the video? I want to better understand if pcloud.com45 supports oembed or not.