How to translate the "You must login to participate in chat" text in Chat widget

Dear Support Team,

I'd like to translate the "You must login to participate in chat" text in the Chat Widget:
http://hataratkelo.com/
You should scroll down a little bit and you can see it in the right sidebar. It must be translated to hungarian. If I logged in, it's OK, but if I logged out, it doesn't work. I checked all the plugin files, and language files but I couldn't find where to translate this single line.
Please help me!
Thank you!
Balazs Szilagyi