Pressing "S" in the demo does nothing, and when I applied the effect in my project, I can't seem to get it working when I preview it.
Huh, I fixed it while I was still typing this. Apparently in my Firefox settings, "webgl.disabled" was userset to "true". I've set it back to "false" and now I can see WebGL effects.
This effect works just fine in my project, but the demo still doesn't work when I press "S".