[keen]

function featureRemover(s) {
    var i = ('' + s).indexOf('&');
    if (i != -1) {
        return ('' + s).substr(0, i);
    }
    return s;
}
 
console.log(featureRemover('_ttp://www.youtube.com/watch?v=kBevzsFGQv8&feature=player_detailpage&something=something2'));
// _ttp://www.youtube.com/watch?v=kBevzsFGQv8