Replace with regex in pre batch script?

So I have files with a name containing a unix timecode and I've made the script in #2 @ https://www.advancedrenamer.com/forum_thread?for um_id=11608?forum_id=11608 work with some altering to fit my format needs but only after I've first processed all the files with a replace regex to remove everything except the timecode in the name.

I would like to be able to do this in one go instead of two but if If I add that replace regex before the script it doesn't work.

Haven't found much info about this pre batch script function but I guess it's what I have to use for this to work.

So how do I add a replace regex there?