Shows a way to create a Participants Database form element that displays an embedded video by using WordPress' built-in video embed filters

pdb-video-element.php

<?php

/**
 * Plugin Name: PDB Video Form Element
 * Description: Demonstrates how to create a Participants Database form element that displays a video
 * Version: 3.0
 * Text Domain: pdb-video-form-element
 * Domain Path: /languages
 * 
 */
class PDb_Video_Form_Element {
  
  /**
   * @var string name of the form element
   */
  private $name = 'video';

  /**
   * 
   */
  public function __construct()
  {
    add_filter( 'pdb-set_form_element_types', array($this, 'video_register_element') );
    add_action( 'pdb-form_element_build_' . $this->name, array($this, 'video_element_building_function') );
    add_filter( 'pdb-before_display_form_element', array($this, 'video_element_value_display_function'), 10, 2 );
  }

  /**
   * adds the form element to the list of form elements
   * 
   * @param array $elements
   * @return array
   */
  public function video_register_element( $elements )
  {
    $elements[$this->name] = __( 'Video', 'pdb-video-form-element' );
    return $elements;
  }

  /**
   * supplies the form element HTML in a write context
   *
   * @param PDb_FormElement $field
   * @return null
   */
  public function video_element_building_function( $field )
  {
    $field->type = 'text-line';
  }

  /**
   * displays the video
   * 
   * this relies on the built-in WP filter that makes an embed out of a URL
   *
   * @param array $value the raw value of the field
   * @param PDb_Field_Item object $field
   * @return string HTML
   */
  public function video_element_value_display_function( $value, $field )
  {
    if ( $field->form_element === $this->name ) {
      $oembed = new WP_oEmbed();
      $value[] = '<div class="pdb-video-container ' . $field->name . '-video">';
      $value[] = $oembed->get_html( $this->extract_url( $field->value )  );
      $value[] = '</div>';
      return implode( PHP_EOL, $value );
    }
    return $value;
  }
  
  /**
   * extracts the URL from the content
   * 
   * this is to clean up a messy content string so that all that remains is the URL
   * 
   * @param string $content
   * @return string the cleaned-up URL
   */
  private function extract_url( $content )
  {
    $output = '';
    
    foreach( explode( ' ', $content ) as $part ) {
      if ( empty( $part ) ) {
        continue;
      }
      $check = filter_var( $part, FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED );
      if ( $check !== false ) {
        $output = $check;
        break;
      }
    }
    
    return $output;
  }

}


new PDb_Video_Form_Element();