front end upload

As long as you know the URL, you can make a shortcode like [KGVID]https://www.yoursite.com/place/where/videos/are/uploaded/video.mp4[/KGVID] so if you wanted to automatically display videos uploaded by users (a dangerous and scary proposition) then you could add something to your template that would check if a video was attached to the form (I don’t use Gravity Forms so I’m not sure of the specifics) then get the URL of the attached video and execute the shortcode. Something like this:

if ( $video_url ) { do_shortcode(''[KGVID]".$video_url."[/KGVID]"); }

I only need to get the thumb of the uploaded video and set it as featured image

There’s no automatic way to generate thumbnails (yet) but you can make thumbnails from any video using the “Embed Video from URL” tab in the “Add Media” popup window. If you make sure “Set generated video thumbnails as featured images.” is turned on in the plugin settings, then the featured image should be set automatically once you choose a thumbnail.

I was wondering how the frontend up loader work with this plugin? And is this possible?

I’m not familiar with the frontend up loader. It might work well. It might not.