I only needed to try this one time, as it also did not work after the first attempt. Instead of translating the content immediately in a quick, un-obstrusive popup, it opens a new browser window in a distractive popup and especially on my slow connection kept connecting to the servers of the app for several minutes. I let it in the background only to notice that the popup had gone missing and nowhere to be seen. On future attempts, holding alt and highlighting text did nothing.