I need to set my jwplayer DVR stream to rewind to -50 seconds on load so when the page is loaded and video starts its automatically delayed 50 seconds from being "LIVE" so any idea how to create a :on load" command? here is my code i need to add it to

<script type="text/javascript" src="https://content.jwplatform.com/libraries/PEeU9yMk.js"></script>
                <script type="text/javascript">jwplayer.key="3SYLbRo6MN5cBDxwpZh3dl1gb0lMTUOos31M5hoAlf4=";</script>
</div>
<script type="text/javascript">
                // jwplayer.key="2U/m9jOYEC49U1j3cNoou7IjxvGS5j03XTpetE5wCVBAwRqhG9pSYWQIMW0=";
                jwplayer.key = '3SYLbRo6MN5cBDxwpZh3dl1gb0lMTUOos31M5hoAlf4=';</script>
<div id="video4">
            </div>
            <script type="text/javascript">
                jwplayer('video4').setup({
                    'skin': 'bekle',
                    logo: {
                        file: '',
                        position: 'top-right',
                        hide: false

                    },
                    'file': "https://bigb9868-bigb9868-us-west-2-ms.global.ssl.fastly.net/bblf23thumb-clips/master/bblf23thumb-clips.m3u8",
                    'title': '',
                    'aspectratio': '16:9',
                    stretching: 'exactfit',
                    'bufferlength': '5',
                    'height': '110px',
                    'width': '620px',
                    'primary': 'hls',
                    'mute': 'true',
                    'controls': 'true',
                    'autostart': 'true',
                    'wmode': 'opaque',
                    'image': '',
                    'abouttext': '',
                    'aboutlink': ''
                });
            </script>