var hash = {
  '.avi'  : 1,
  '.dv' : 1,
  '.mov' : 1,
  '.qt' : 1,
  '.mp4' : 1,
  '.mpeg' : 1,
  '.3gp' : 1,
  '.asf' : 1,
  '.wmv' : 1,
  '.mpg': 1,
  '.AVI': 1,
  '.DV': 1,
  '.MOV': 1,
  '.QT': 1,
  '.MP4': 1,
  '.MPEG': 1,
  '.3GP': 1,
  '.ASF': 1,
  '.WMV': 1,
  '.MPG': 1
};

function check_extension(filename, submitId) {
    var re = /\..+$/;
    var ext = filename.match(re);
    var submitEl = document.getElementById(submitId);
    if (submitEl) {
        if (hash[ext]) {
            submitEl.disabled = false;
            return true;
        } else {
            alert("The file type you have entered is not accepted.\n\nYou must enter a video file in one of the following formats: .avi, .dv, .mov, .qt, .mp4, .mpeg, .3gp, .asf, .wmv, .mpg.");
            submitEl.disabled = false;

            return false;
        }
    }
}