Thanks. It appears to be a problem within Firefox (28.0 Mac) on my computer. The plugin works fine in Safari and Chrome. As you can see in the screenshot, changing the setting on the web site didn't help. I put a copy of Firefox and Chrome side by side on my screen to find the appropriate setting in Firefox. I chose English and it changed the web page language to whatever is shown in this screen shot. Not English. Very odd. As a reminder, the plugin has been uninstalled, program restarted, and plugin reinstalled.
Web site after finding and changing language to English