Gruveo is an excellent anonymous Flash/browser based very simple video\audio chat website). Due to some weird bug in Ubuntu 13.10 which doesn't allow to change camera settings on individual website (such as Gruveo) through Flash settings popup, following workaround can be used through Flash's global settings.

Visit http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager06.html Select monitor with the eye tab (5th from the left), scroll down and select required site, http://www.gruveo.com, and then click radio button "Always Allow" (see following screenshot). Restart the browser and refresh gruveo again. The video chat is now working.