Install this plugin – https://wordpress.org/plugins/user-role-editor/ ( User Role Editor )
Then go to your wp dashboard > users, and choose the user you want to add video gallery roles.
The roles are
video_gallery_edit_options – edit video gallery > settings
video_gallery_edit_others_galleries – he can edit all galleries
video_gallery_edit_own_galleries – he can only create and edit his own galleries
video_gallery_edit_player_configs – create video player configurations
First of all you will need this plugin – User Role Editor