Edit in JSFiddle

webshim.setOptions('mediaelement', {
    replaceUI: 'auto',
    jme: {
        barTemplate: '<div class="play-pause-container">{{play-pause}}</div>' +
        //here is your new jump-10 plugin:
        '<div class="jump-container">{{jump-10}}</div>' +
            '<div class="playlist-container"><div class="playlist-box">{{playlist-prev}}{{playlist-next}}</div></div>' +
            '<div class="currenttime-container">{{currenttime-display}}</div>' +
            '<div class="progress-container">{{time-slider}}</div>' +
            '<div class="duration-container">{{duration-display}}</div>' +
            '<div class="mute-container">{{mute-unmute}}</div>' +
            '<div class="volume-container">{{volume-slider}}</div><div class="subtitle-container">' +
            '<div class="subtitle-controls">{{captions}}</div></div>' +
            '<div class="fullscreen-container">{{fullscreen}}</div>'
    }
});

webshim.polyfill('mediaelement');

webshim.ready('jme', function () {
    $.jme.registerPlugin('jump-10', {
        structure: '<button class="{%class%}" type="button">&gt;&gt;</button>',
        _create: function ($control, $media, $base) {
            var enableDisable = function () {
                var notReady = !$media.prop('readyState');
                $control.prop('disabled', notReady);
            };

            $control.on('click', function () {
                $media.prop('currentTime', $media.prop('currentTime') + 10);
            });

            $media.on('emptied loadedmetadata', enableDisable);
            enableDisable();
        }
    });
});

<div class="player">
    <div class="mediaplayer">
        <video poster="http://corrupt-system.de/assets/media/sintel/sintel-trailer.jpg" controls preload="none">
            <source src="http://corrupt-system.de/assets/media/sintel/sintel-trailer.m4v" type="video/mp4" />
            <source src="http://corrupt-system.de/assets/media/sintel/sintel-trailer.webm" type="video/webm" />
        </video>
    </div>
</div>
<p>This example adds a new control called 'jump-10' to the controlbar</p>

.player {
    margin: auto;
    padding: 10px;
    width: 90%;
    max-width: 900px;
    min-width: 320px;
}
.mediaplayer {
    position: relative;
    height: 0;
    width: 100%;
    padding-bottom: 56.25%;
    /* 16/9 */
}
.mediaplayer video, .mediaplayer .polyfill-video {
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 100%;
}
.jump-10[disabled] {
	color: #999;
	cursor: not-allowed;
}