Fixed fatal error with videos

system/src/Grav/Common/Page/Medium/Medium.php

@@ -111,6 +111,17 @@ class Medium implements RenderableInterface, MediaFileInterface, JsonSerializabl
         $this->unserializeMediaObjectTrait($data);
     }
 
+    /**
+     * TODO: do we want this in base medium?
+     *
+     * @return ImageMediaInterface
+     * @phpstan-pure
+     */
+    public function higherQualityAlternative(): ImageMediaInterface
+    {
+        return $this->getThumbnail();
+    }
+
     /**
      * @return array
      * @phpstan-pure