I was using JWPlayer 5, but right now moving to JWPlayer 6.
<script>
jwplayer('myElement2').setup({
file: 'intro.mp4',
image: 'intro.png',
skin: 'stormtrooper',
icons: 'false' // this doesn't work on JWPlayer 6
});
jwplayer('myElement2').getPlugin("display").hide();
</script>
On JWPlayer 5 it was icons: 'false'
and there were no play button.