1 line search box is the kinda shitty effort I expect from Microsoft and lame Explorer crappy search tool/ui ... and whole dumb input your advanced query via keyboard regex etc..
my suggestion would be to at least provide some sort of enhanced UI like Locate32 so you can easily make changes to Extensions etc etc etc, so I can leave a whole bunch of extensions like common video or image ones.. in the extension box.. and next time I open up the program my last used extensions are saved if I so choose..also the drop down menu means I can swap between previously entered results.. way better
oh and on the Better UI.. would be nice if it were possible to at least have a thumbnail view, and type column sorting.. heck just COPY LOCATE32