Embed a background video with a child theme for Zerif Lite

Hi,

I would like to embed a you tube video background under a child theme (my current one is ResponsiveBoat) of the Zerif lite. I looked up the following post:
https://www.ads-software.com/support/topic/how-can-i-embed-a-video-on-front-page/?replies=21

But I still can’t get this to work. I tried pasting it in both parent (Zerif Lite) and child theme (ResponsiveBoat)
Appearance->Editor->big_title.php

and also just on the child theme (ResponsiveBoat) big_title.php like the following: But it’s not loading. I could see that youtube was in the loading bar while the page was reloading but nothing came up. Could someone help please on how to embed a video background into the ResponsiveBoat child theme? It will be much appreciated.

echo ‘</div>’;

echo ‘</div><!– .header-content-wrap –>’;

endif;

echo ‘<iframe width=”420″ height=”315″ src=”https://www.youtube.com/embed/L7EKdzT6w1k&#8221; frameborder=”0″ allowfullscreen></iframe>’;

echo ‘<div class=”clear”></div>’;

?>

</div><!–.home-header-wrap –>