To prevent black bars and have a responsive embedded Teleport player a script based embed is required. Here is an example:
<div style="max-width: 750px">
<script src="//www.teleport.io/api/v2/player?feedid=mthayes&containeraspectratio=auto"></script>
</div>
Simply change your embed codes from iframe to script based scripts. View more detailed information herel.