core-bundle/src/Resources/contao/elements/ContentYouTube.php
public function generate()
	{
		if ($this->youtube == '')
		{
			return '';
		}

		if (TL_MODE == 'BE')
		{
			$return = '<p><a href="https://youtu.be/' . $this->youtube . '" target="_blank" rel="noreferrer noopener">youtu.be/' . $this->youtube . '</a></p>';

			if ($this->headline != '')
			{
				$return = '<'. $this->hl .'>'. $this->headline .'</'. $this->hl .'>'. $return;
			}

			return $return;
		}

		return parent::generate();
	}
public function generate()
	{
		if ($this->youtube == '')
		{
			return '';
		}

		if (TL_MODE == 'BE')
		{
			$return = '<p><a href="https://youtu.be/' . $this->youtube . '" target="_blank" rel="noreferrer noopener">youtu.be/' . $this->youtube . '</a></p>';

			if ($this->headline != '')
			{
				$return = '<'. $this->hl .'>'. $this->headline .'</'. $this->hl .'>'. $return;
			}

			return $return;
		}

		return parent::generate();
	}
Show the YouTube link in the back end

@return string