The Google Drive SDK console only allows you to enter MIME types and file extensions one at a time. This script allows you to enter a comma-separated list of values into a text box and then have it split into multiple text boxes automatically.

drive_console_helper.js

(function() {
  // Include jQuery.
  var script = document.createElement('script');
  script.src = 'https://code.jquery.com/jquery-2.1.1.min.js';
  script.type = 'text/javascript';
  document.getElementsByTagName('head')[0].appendChild(script);

  var sections = [
    'Default MIME Types',
    'Default File Extensions',
    'Secondary MIME Types',
    'Secondary File Extensions'
  ];
  sections.forEach(function(section) {
    var header = $('h4:contains("' + section + '")');
    var inputs = header.nextUntil('h4').find('input');
    var values = inputs.get().reduce(function(result, input) {
      var value = $(input).val();
      var parts = value.split(',');
      if (parts.length > 1) {
        $(input).val(parts.shift());
        result = result.concat(parts);
      }
      return result;
    }, []);
    var keypressEvent = jQuery.Event('keypress', {which: 65, keyCode: 65});
    // Dummy handler is added so .trigger() will fire correctly.
    var keypressHandler = function() {};
    values.forEach(function(value) {
      header.nextUntil('h4').find('input:last')
          .val(value)
          .keypress(keypressHandler)
          .trigger(keypressEvent);
    });
  });
})();

// Compressed
// (function(){var e=document.createElement("script");e.src="https://code.jquery.com/jquery-2.1.1.min.js";e.type="text/javascript";document.getElementsByTagName("head")[0].appendChild(e);var t=["Default MIME Types","Default File Extensions","Secondary MIME Types","Secondary File Extensions"];t.forEach(function(e){var t=$('h4:contains("'+e+'")');var n=t.nextUntil("h4").find("input");var r=n.get().reduce(function(e,t){var n=$(t).val();var r=n.split(",");if(r.length>1){$(t).val(r.shift());e=e.concat(r)}return e},[]);var i=jQuery.Event("keypress",{which:65,keyCode:65});var s=function(){};r.forEach(function(e){t.nextUntil("h4").find("input:last").val(e).keypress(s).trigger(i)})})})()