Speed Bumps – Example code

one.php

<?php
	register_speed_bump( 'rickroll', array(
		'string_to_inject' => function() { return '<iframe width="420" height="315" src="https://www.youtube.com/embed/dQw4w9WgXcQ" frameborder="0" allowfullscreen></iframe>'; },
		'minimum_content_length' => false,
		'from_start' => false,
		'from_end' => false,
	));
	add_filter( 'the_content', 'insert_speed_bumps', 1 );