Removing channel from the options object allows it to play for me:
<script src= "//player.twitch.tv/js/embed/v1.js"></script>
<div id="player"></div>
<script type="text/javascript">
var options = {
width: 854,
height: 480,
video: "v75527399"
};
var player = new Twitch.Player("player", options);
player.setVolume(0.5);
</script>
(Note: I removed the protocol from the script source since Chrome blocked Codepen from accessing mixed content sources.)