Why does my element is not visible with z-index 10000
<p>I am developping a website with youtube videos, and I am using mb.YTPlayer plugin. You can see it here : <a href="http://orthopluss.fr/test/index.html#prestations" rel="nofollow">http://orthopluss.fr/test/index.html#prestations</a></p>

<p>There are two arrows, one on the right, one on the left, which I would like to put ON the video. For example, if I take the left arrow and remove the margin-left, the arrow is positioned behing the video.
I tried adding a z-index : 10000 on the #timelapse-prev button but it doesn't get the button in front of the video. </p>

<p>I have been to do it on the demo plugin page (using the developper tools) : <a href="http://pupunzi.com/mb.components/mb.YTPlayer/demo/demo_as_player.html" rel="nofollow">http://pupunzi.com/mb.components/mb.YTPlayer/demo/demo_as_player.html</a> so I am assuming that's something from my page that causes an issue... </p>

<p>I tried many things (setting other z-index differentely) but it has no effect. Do you have an idea what would cause such a behavior ?</p>

<p>Thanks !!</p>