Download Column Thumbnail

add_filter( 'manage_edit-download_columns', 'cor_edd_manage_edit_download_columns' );

/**

 * Insert the thumbnail column.

 */

function cor_edd_manage_edit_download_columns( $columns ) {

	//Below code will add new column without any text

	$column_thumbnail = array( 'icon' => false );

	// Below code will show Thumbnail text in column

	//$column_thumbnail = array( 'icon' => 'Thumbnail' );

	return array_slice( $columns, 0, 1, true ) + $column_thumbnail + array_slice( $columns, 1, null, true );

}

add_action( 'manage_download_posts_custom_column', 'cor_edd_manage_download_posts_custom_column' );

/**

 * Get the thumbnail.

 */

function cor_edd_manage_download_posts_custom_column( $column_name ) {

	global $post;

	if ( 'icon' === $column_name ) {

		echo get_the_post_thumbnail( $post->ID, array( 80, 60 ) );

	}

}

add_action( 'admin_print_styles-edit.php', 'cor_edd_admin_print_styles_edit' );

/**

 * Column thumbnail specific styles.

 */

function cor_edd_admin_print_styles_edit() {

	$screen = get_current_screen();

	if ( 'edit-download' === $screen->id ) {

		?>

		<style>

			.fixed .column-icon {

				text-align: center;

			}

			.fixed .column-icon img {

				display: inline-block;

				width: auto;

				max-width: 80px;

				height: auto;

				max-height: 60px;

				border: 1px solid #e7e7e7;

				border: 1px solid rgba(0, 0, 0, 0.07);

			}

		</style>

		<?php

	}

}