Sadly I can't use it because it is incompatible with blocker/firewall add-ons. This add-on requires java script "on" in google page. If an add-on turns off java in google page, sadly 2ColumnGoogleResults doesn't work.
Who knows in the the future, the developer will find a way to make it works without java scripts.
I installed this addon and fully satisfied. Is it possible that user will be able to expand the power of this addon on any site by clicking some button? Wide screens aren't so comfortable for eyes and why not to give to user the ability to switch to 2 columns for any site that he wants? If some particular 2-columns layout will not be applicable for him (or he won't like it) he will be able to return to original layout like now.
Thank you for the update. I disabled all my other browser plugins but it is not working correctly. I uploaded a video to show you the problem: https://mega.nz/#!1fIWSaqa!LKucetR8dwcOo19CrwQ5YbkQRXHZB7GDXh8GppSfjuk Thank for so work!
I appreciate it works together with the add-on uAutoPagerize. I would be happy if this add-on had an easy on/off button. Sometimes 2-colums results are a bit inconvenient, for example when I browse in Google pictures. Or when I temporarily use only half a monitor for browsing.