the builtin search does not highlight keywords on the target pages link smartsearch does to fix this:
edit file components/com_jdownloads/views/search/tmpldefault_results.php:
add at line 12
<?php
$searchword= base64_encode(htmlspecialchars($_POST["searchword"]));
?>
Change line 21
<a href="<?php echo JRoute::_($result->href); ?>"<?php if ($result->browsernav == 1) :?> target="_blank"<?php endif;?>>
to:
<a href="<?php echo JRoute::_($result->href); ?>?highlight=<?php echo $searchword ?>"<?php if ($result->browsernav == 1) :?> target="_blank"<?php endif;?>>
It is not 100%
For example
input: download example
mine code WyJkb3dubG9hZCBleGFtcGxlIl0= > ["download example"]
smartsearch WyJkb3dubG9hZCIsImV4YW1wbGUiLCJkb3dubG9hZCBleGFtcGxlIl0= > ["download","example","download example"]
I played a bit with JHtml::_('behavior.highlighter', $array) but couldn`t get it to work. Maybe it is even the wrong function. :P