first of all, I love the idea of this plugin and am so glad to have found it! I am using version 1.4.3 with wp 3.5.1.
when installing though, I got the message that I was missing and needed to download opting, and gifsicle. I tried clicking and having them installed, but it didn't work. to be honest, I've no need for either of them as my site is comprised of jpegs and they are all I plan on using. can I use the plugin without downloading the other options? I disabled both options in settings and the warning went away.