How to fetch all videos in custom page which uploaded in wp-admin (Media) in wordpress

Question

Uploaded images, video’s etc. are stored as posts with the type “attachment”; use get_posts( ) with the right parameters.

Try this; the code loops trough all attachments and displays them:

$args = array(
  'post_type' => 'attachment',
  'numberposts' => -1,
  'post_status' => null,
  'post_parent' => null, // any parent
  'post_mime_type' => 'YOUR-POST-MIME-TYPE'
); 

$attachments = get_posts( $args );

if ( $attachments ) {
  foreach ( $attachments as $post ) {
    setup_postdata( $post );
    the_title( );
    the_attachment_link( $post->ID, false );
    the_excerpt( );
  }
}

Where YOUR-POST-MIMET-YPE is the mime-type you’re looking for.

A full or partial mime-type, e.g. image, video, video/mp4, which is matched against a post’s post_mime_type field

So in your case you should try video.
You also could use array( 'video', 'another-mime-type' ) for multiple mime-types.