jquery.gallerific.js implements a page-wide keydown handler that captures the spacebar and stops it from functioning.

934 if (this.enableKeyboardNavigation) {

935  $(document).keydown(function(e) {

936   var key = e.charCode ? e.charCode : e.keyCode ? e.keyCode : 0;

937   switch(key) {

938    case 32: // space

939     gallery.next();

940     e.preventDefault();

941     break;

If you scroll back to the gallery portion of the document while still focusing the form, you will notice that pressing the spacebar progresses to the next image.