Glad to have found this, it was bugging me for a while. I did run into one slight issue when trying to set it up.
I'm not sure why Value Display HTML: <a href="{$valueURL}">{$value}</a> does not work but making it <a href="{$value}">{$value}</a> does.
When I had it setup like in the picture it was trying to append the $valueURL to the forum web address.