As you can see in the screenshot the Shockwave Flash Plugin is disabled. In the German Firefox you can't read the text of the click-to-activate option in the dropdown. All you can read is: "Nachfragen, ob ak…" It's not clear at all what "ak" means (the full text is "Nachfragen, ob aktiviert werden soll). There is a tooltip so it's possible to understand the option when hovering over the option but it's a usability regression that the tooltip is needed to understand this option. I don't think the width of the selection field has to be restricted that much.

This is already fixed by bug 1499294 as I noted in bug 1499666.