I finally managed to solve this. Next: replacing jwplayer with jplayer.
<a class="jwVideo" spline-01.mp4" rel="group"> Preview </a>
$(function() {
$("a.jwVideo").click(function() {
var myVideo = this.href; // Dont forget about 'this'
$.fancybox({
padding : 0,
content: '<div id="video_container">Loading the player ... </div>',
afterShow: function(){
jwplayer("video_container").setup({
file: myVideo,
width: 640,
height: 385,
modes: [
{ type: 'html5' },
{ type: 'flash', src: 'assets/jwplayer/jwplayer.flash.swf' }
]
});
}
});
return false;
});
});