Sending shortcode string to admin-ajax

AJAX and PHP aren’t my strengths, but I’m attempting to create a call that swaps out an existing plugin gallery with a new one. It works for the most part, but the gallery it returns is wrong, same as if the string inside of the shortcode is empty.

Could I get an extra set of eyes on this to make sure it isn’t some syntax error?

First the inital shortcode is rendered into the html. Clicking a link sends a new parameter to a js function in the header:

<div id="vidGalleryContent">
[tubepress mode="playlist" resultsPerPage='20' output='searchResults' searchProvider='youtube'  playlistValue='PLMffcFdm_7-HT1HiVkNEguRtiYkhgq0TC']
</div>

<a href="#" onclick="swapVidGallery('PLMffcFdm_7-Hi6NibMNpEuc8rlqbBNxC8')">Change gallery</a>

Then the header script puts the parameter string inside a new shortcode string and sends it off to functions.php:

function swapVidGallery(vidID){
      var  newGalleryParameter = "[tubepress resultsPerPage='20' output='searchResults' searchProvider='youtube'  mode='playlist' playlistValue='"+vidID+"']";
jQuery.ajax({
        type:"POST",
	url: 'http:\/\/mysite.com\/wp-admin/admin-ajax.php',
        data: {action: 'newVidGallery',
        'newGalleryShortcode':newGalleryParameter},
	success: function(result){
		jQuery('#vidGalleryContent').html(result);
		console.log(result);
	}
	});
};

… And finally functions.php renders the shortcode with do_shortcode() and sends the html back to the page:

add_action('wp_ajax_newVidGallery', 'newVidGallery_function');
add_action('wp_ajax_nopriv_newVidGallery', 'newVidGallery_function');

function newVidGallery_function() {
	$newVidGalleryPOST = $_POST['newGalleryShortcode'];
    echo do_shortcode($newVidGalleryPOST);	
	die();
}

At least that’s what’s *supposed* to be happening. What’s going wrong?

And help is appreciated. ~gyz