Please, explain to me what are the pitfalls to use ZURB Foundation's `flex-video` instead of `responsive-embed` (or vice versa). I've made a layout where I don't see any difference between two:

	<!-- .flex-video -->
	<div class="small-12 columns">
		<div class="flex-video">
			<object data="example_youtube_url"></object>
		</div>
	</div>

	<!-- .responsive-embed -->
	<div class="small-12 columns">
		<div class="responsive-embed">
			<object data="example_youtube_url"></object>
		</div>
	</div>

They behave the same. What should I choose and why?