I am running Ubuntu 12.10, and Heromachine worked without a problem on it as recently as a couple of months ago (when I last used it). The problem does not seem to be tied to the browser, as it exists for me in both Chromium and Firefox. I’m pretty sure that it’s tied to either a recent package update in Ubuntu or a recent update in Flash that didn’t percolate into the Linux versions since they are no longer supported by Adobe on account of them being jerkfaces. I haven’t tried using Chrome yet, but that’s next on my list.