Hi,
try this javascript function in your user control page.
<script type="text/javascript">
function cellSelected(sender, args) {
var mediaUrl = args.get_gridDataItem().getDataKeyValue("MediaUrl");
document.getElementById("<% =hdnMediaUrl.ClientID %>").value = mediaUrl;
}
function cellDeselected(sender, args) {
var mediaUrl = args.get_gridDataItem().getDataKeyValue("MediaUrl");
document.getElementById("<% =hdnMediaUrl.ClientID %>").value = '';
}
</script>
then let me know if it is working or not.
Thanks
Tapan kumar