With Flexi you can let your visitors to submit video URLs from video streaming sites like YouTube.com, Vimeo.com. Just copy the URL of the video and paste it. It will auto generate the thumbnail and display it in gallery.
Next step is to create a submission form where we submit only video. Since thumbnail is auto created we don't need any image field. Just require a mandatory fields Title & URL field.
Check the video below, which will demonstrate how the form is build and video is displayed for the first time and new wordpress installation.