Allowing Kaltura video source as Drupal media
This module provides Drupal 8/9, using the Media module, with a custom media source definition to allow users to add videos from services such as Kaltura. Some media sources are not known to Drupal or Media entities. This module provided an example of adding a media source Drupal recognizes and allows rendering of the media entity.
Using the hook_media_source_info_alter hook we can register a media source with Drupal / Media module to recognize the new addition. The hook_form_FORM_ID_alter hook is used to add some validation so users can enter the correct video source and build iframe/screenshots from a given media source. The Drupal\kaltura_media\Form\KalturaForm allows us to extend the media add/edit form and provide a similar media creation/editing experience in Drupal. There is additional validation to ensure the host is from kaltura.com, so the iframe rendering of the video player from Kaltura is properly rendered and provided. Lastly, Drupal's field formatter plugin is used to build out the iframe with video ID and HTML rendering attributes (width, height, etc), see Drupal\kaltura_media\Plugin\Field\FieldFormatter\KalturaVideoFormatter.