[Plugin: Video Thumbnails] reset thumbnail for all posts

Yikes! Very sorry that this happened to you. I believe there are some bulk deletion plugins that you could use to clear all attachments.

As for resetting all of the video thumbnails, you should be able to make a small change so that when you use the “scan past posts” option it will clear the custom field for video thumbnails.

In video-thumbnails.php just change this:

function video_thumbnails_past_callback() {
	global $wpdb; // this is how you get access to the database

	$post_id = $_POST['post_id'];

	// Clear video thumbnail meta before scanning
	delete_post_meta( $post_id, '_video_thumbnail' );

	echo get_the_title( $post_id ) . ' - ';

	$video_thumbnail = get_video_thumbnail( $post_id );

	if ( is_wp_error( $video_thumbnail ) ) {
		echo $video_thumbnail->get_error_message();
	} else  if ( $video_thumbnail != null ) {
		echo '<span style="color:green">✔</span> Success!';
	} else {
		echo '<span style="color:red">✖</span> Couldn\'t find a video thumbnail for this post.';
	}

	die();
}

to this:

function video_thumbnails_past_callback() {
	global $wpdb; // this is how you get access to the database

	$post_id = $_POST['post_id'];

	// Clear video thumbnail meta
	delete_post_meta( $post_id, '_video_thumbnail' );

	echo get_the_title( $post_id ) . ' - Video Thumbnail meta deleted';

	die();
}

Now when you run the “scan past posts” option on the settings page it will instead clear the video thumbnail information stored with the post. Once you undo the change, you can “scan past posts” normally and it will find new thumbnails.

Let me know if you need any more help. I’m in the process of version 2.0 and one of the changes is that all media uploaded as a video thumbnail is specially tagged so that if this type of bug happened again they can all be deleted with one click.