Rated 4 out of 5 stars

Version 1.1.0 seems to be missing the ability to use regular expression filters. (Even the check box is gone)

Fortunately you can still get version 1.0.4 at http://code.downthemall.net/releases/downthemall-1.0.4.xpi

This review is for a previous version of the add-on (1.1.0). 

Actually you can create regexp filters in 1.1 or use them in fast-filtering.
Just enclose the expression like so:
/expr/
You may even form an expression consisting of different expressions, like so
/expr/,*.ext,/expr2/