@miedward

Reroll of #3 which isn't applying at least with 10.2.x

drunken monkey → credited miedward → .

Recreated #2 as a patch because I'm not sure about installing from a core fork

I thought this was working but I was wrong. The approach I went with in the end is this

/**
 * Implements hook_editor_js_settings_alter
 */
function mymodule_editor_js_settings_alter(array &$settings) {
  // Settings for ckeditor4 youtube plugin responsive setting to be the default
  foreach ($settings['editor']['formats'] as $name => $value) {
    $settings['editor']['formats'][$name]['editorSettings']['youtube_responsive'] = TRUE;
  }
}

I made an issue fork and things before I realized this is probably not desired default behavior but I'm going to put the patch here if people want it to work that way without making a separate module.

miedward → made their first commit to this issue’s fork.