function validate(id) {
    var OK = new Array ('3gp', 'avi', 'flv', 'm4v', 'mkv', 'mov', 'mp4', 'mpeg', 'swf' );
   var filename = document.getElementById(id).value;
   var ext = getExt(filename);
   var fileOK = 0;
 
   for (i = 0; i < OK.length; i++) {
     if (OK[i] == ext) {
      fileOK = 1; // one of the file extensions found
     } 
   }
 
   if (fileOK == 0) { 
       alert ("The file you specified is not a supported video type.\n\n  Please select a video file with one of the following extensions: \n\n * .3gp\n * .avi\n * .flv\n * .m4v\n * .mkv\n * .mov\n * .mp4\n * .mpeg\n * .swf\n");
     return false;
   }
}
 
function getExt(filename) {
   var dot_pos = filename.lastIndexOf(".");
   if(dot_pos == -1)
      return "";
   return filename.substr(dot_pos+1).toLowerCase();
}