Only show users own media files (little bit hackery)

gistfile1.aw

<?php

add_action( 'pre_get_posts', 'media_filter_user' );
add_filter( 'query', 'media_filter_counter' );

// Main stuff that filters it
function media_filter_user( $query ) {
	global $pagenow;

	if(  'media-upload.php' == $pagenow ) {
		$query->set( 'author', get_current_user_id() );
	}
}

// Fix queries so the counter is right of all the media types
function media_filter_counter( $query ) {
	global $pagenow, $mime_type, $wpdb;

	if( ! is_super_admin() && 'media-upload.php' == $pagenow ) {
		$traces = debug_backtrace();

		if( isset( $traces[ 5 ] ) && 'wp_count_attachments' == $traces[ 5 ]['function'] ) {

			if( strstr( $query, 'SELECT post_mime_type' ) ) {
				$and = wp_post_mime_type_where('');
				return "SELECT post_mime_type, COUNT( * ) AS num_posts FROM $wpdb->posts WHERE post_type = 'attachment' AND post_status != 'trash' AND post_author = " . get_current_user_id() . " $and GROUP BY post_mime_type";
			}
			else {
				$and = wp_post_mime_type_where('');
				return "SELECT COUNT( * ) FROM $wpdb->posts WHERE post_type = 'attachment' AND post_status = 'trash' $and";
			}
		}
		else if( 'get_available_post_mime_types' == $traces[ 5 ]['function'] ) {
			$query = "SELECT DISTINCT post_mime_type FROM $wpdb->posts WHERE post_type = 'attachment' AND post_author = " . get_current_user_id();
		}
	}

	return $query;
}