Trik Theme DeeTube: Video Poster pakai GoogleBook Cover

Untuk Thumbnail ada di functions.php

ganti:
		<a class="clip-link" data-id="'.$post->ID.'" title="'.esc_attr(get_the_title($post_id)).'" href="'.get_permalink($post_id).'">
			<span class="clip">
				<img src="'.$thumb_url.'" alt="'.esc_attr(get_the_title($post_id)).'" /><span class="vertical-align"></span>
			</span>

			<span class="overlay"></span>
		</a>
menjadi:
		<a class="clip-link" data-id="'.$post->ID.'" title="'.esc_attr(get_the_title($post_id)).'" href="'.get_permalink($post_id).'">
			<span class="clip">
				<img src="https://books.google.co.id/books/content?id='.$thumb_url.'&printsec=frontcover&img&edge=curl" alt="'.esc_attr(get_the_title($post_id)).'" /><span class="vertical-align"></span>
			</span>

			<span class="overlay"></span>
		</a>

Untuk Tampilan Full setelah Readmore adanya di single.php

ganti:
echo '<div id="thumb" class="rich-content"><img src="'.$thumb_url.'" alt="'.esc_attr(get_the_title($post->ID)).'" /><span class="vertical-align"></div>';

menjadi:
echo '<div id="thumb" class="rich-content"><img src="https://books.google.co.id/books/content?id='.$thumb_url.'&printsec=frontcover&img=1&zoom=1&edge=curl" alt="'.esc_attr(get_the_title($post->ID)).'" /><span class="vertical-align"></div>';