Here is the code to add next, previous buttons to acidfree images. The images are ordered according to weightings. Place the code in template.php in your theme directory. (I know, I know, i'm supposed to use joins...). It works for both images and videos in acid free.

<?php
function next_prev_acidfree($current_nid, $label, $class) {
	# get its parent
	$query = db_query("SELECT parent FROM `acidfree_hierarchy` WHERE child = $current_nid;");
	$parent = db_result($query);
	
  	# root gallery
	if ($parent == -1) {
  		$arr ['parent'] = l("Photo Gallery", 'acidfree', array("title" => $label, "class" => $class));
  	}else {
  		# Get the parent
  		$query = db_query("SELECT title FROM `node` WHERE nid = $parent;");
  		$parent_title = db_result($query);
  		$arr ['parent'] = l($parent_title, 'node/'.$parent, array("title" => $label, "class" => $class));
  	}
  		  
	# Get all the other photos videos that have the same parent
	
	  //$sql = "SELECT n.nid, n.title FROM {node} n INNER JOIN {term_node} t ON n.nid = t.nid ";
	  $sql = "SELECT a.aid, n.title, nid FROM {node} n, {acidfree} a, {acidfree_hierarchy} ah ".
	  		" WHERE n.type='acidfree' AND n.nid = a.aid AND (a.class='photo' || a.class='video')".
	  		" AND ah.parent = $parent AND ah.child=a.aid ".
	  		" ORDER BY a.weight ASC, n.nid DESC";
	  
	  
	  $result = db_query($sql);

	  if (!db_num_rows($result)) {
	    $arr ['next'] = null;
	    $arr ['previous'] = null;
	  } else {
	  	while ($row = db_fetch_array($result)) {
	  		if ($row['nid'] == $current_nid && $before) {
	  			$arr ['previous'] = l("< < Previous", "node/".$before['nid'], array("title" => $label, "class" => $class));
	  		} 
	  		if ($before['nid'] == $current_nid) {
	  			$arr ['next'] = l("Next > >", "node/".$row['nid'], array("title" => $label, "class" => $class));
	  		}
	  		
	  		$before = $row;
	  	}
	  }
	  return $arr;
}

function phptemplate_display_next_previous($node) {
	$arr = next_prev_acidfree($node->nid, 'Navigation', 'test');
  	
  	//echo $previous . " | " . $next ."";
    $output .= "<table class='acidfree-next-previous'>";
    $output .= "<tr>";
    $output .= "<td class='acidfree-previous'>".$arr['previous']."</td>";
    $output .= "<td class='acidfree-parent'>".$arr['parent']."</td>";
    $output .= "<td class='acidfree-next'>".$arr['next']."</td>";
    $output . "</tr>";
    $output .= "</table>";
    return $output;
}

function phptemplate_acidfree_print_full_photo(&$node) {
    if (!$node->small)
        return '';
    $output .= acidfree_pager_creator($node);

    $output .= phptemplate_display_next_previous($node);
    $output .= "<div class='acidfree-full'>";
    $largeurl = _acidfree_get_large_url($node);
    if (!$largeurl) {
        $output .= theme('image', _acidfree_get_small_url($node),
                $node->title, $node->title, NULL, false);
    } else {
        $output .= "<a href='"._acidfree_get_large_url($node)."'>".
            theme('image', _acidfree_get_small_url($node),
                    $node->title, $node->title, NULL, false).
            "</a>";
    }
    $output .= "</div><div class='acidfree-body'>{$node->body}</div>";
    if (variable_get('acidfree_show_exif_data', false)) {
        $output .= theme('acidfree_exif_data', $node);
    }

    return $output;
}

function phptemplate_acidfree_print_full_video(&$node) {
    if (!$node->large)
        return '';

    // get the pager
    $output = acidfree_pager_creator($node);
    $output .= phptemplate_display_next_previous($node);

    $id = $node->nid;
    $name = $node->title;

    // icon link to the full size video
    $full_video = _acidfree_get_large_url($node);
    $output .= "<a href='$full_video'>".t('download video').'</a><br/>';

    $ext = pathinfo(_acidfree_get_large_path($node), PATHINFO_EXTENSION);
    switch ($ext) {
    case 'rm':
        $type = 'realmedia';
        break;
    case 'mp4':
    case 'mov':
        $type = 'quicktime';
        break;
    default:
        $type = 'windowsmedia';
        break;
    }
    $finfo = image_get_info(_acidfree_get_small_path($node, true));
    $node->videoy = $finfo['height'];
    $node->videox = $finfo['width'];
    $output .= acidfree_call("theme_video_{$type}_control",Array(&$node));
    $output .= "<div class='acidfree-body'>{$node->body}</div>\n";
    return $output;
}
?>

code ..............................