Adding videos to slider

Hi, I would like to do the same thing. I created a child theme and added the style.css and element-slider.php file but I’m not sure how to alter the code to allow it to accept videos in the slider. Here is the code:

<div class="flex-container">

	<!--slideshow-->

	<div class="flexslider">
	 	<ul class="slides">

<?php for ($i = 1; $i <= 2; $i++) { ?>

<li>
			  <a>"><img src="<?php if(esc_url(of_get_option('slider_image'.$i)) != NULL){ echo esc_url(of_get_option('slider_image'.$i));} else echo get_template_directory_uri() . '/images/slide'.$i.'.jpg' ?>" alt="<?php echo esc_html(of_get_option('slider_head'.$i)); ?>" /></a>
			 <?php if(of_get_option('slider_caption') != "off") { ?>
			<p class="flex-caption"><?php if(esc_html(of_get_option('slider_head'.$i)) != NULL){ echo esc_html(of_get_option('slider_head'.$i));} else echo "Nullam posuere felis a lacus tempor eget dignissim arcu adipiscing." ?><p>
			 <?php } ?>
			</li>
			<?php } ?>

</div> <!--slideshow end-->

  </div><!--flex container end-->

  <div class="clear"></div>

Can you help me figure out what needs to be changed? Thanks a lot for your help!