Repeating rename with regexp

Now that regular expressions support repeating, I'd like to ask some help on how to change my quick rename button.

What my button does is it a) converts underscore to space and b) removes brackets and text inside them.

Now, I have it set that it removes the brackets if I have a file like this:

[blahblah] video file 01 [A3BC559Y].avi

I remove the brackets and the text in them with this regular expressions:

([.+]) (.+) ([.+])(..+) -> \2\4

This gives me video file 01.avi.

Now, this works fine as long as there's a space before and after "video file 01". But it won't work if the file name is for example something like this:

[blahblah]video file 01[A3BC559Y].avi
with no spaces or there's a space between one of the bracket and the file name on either side.

So with repeating regular expressions, how would I make the rename check for all possible combinations of space/no space and then removing the brackets and anything inside them, leaving just the file name and extension?

EDIT: Found it in an older post, no need to reply. Sorry.