Openfire 4.0.3 over ubuntu 14.04, plugin Openfire Meetings video meeting problem

I Download and install a fresh version openfire_4_0_3, install only the pluggin Openfire Meetings.

I start a conference, invite several participants, but on each screen, small black boxes are observed, without image.

I install Openfie following steps readme

Installation and Configuration

PLEASE NOTE - You will need at Least Openfire 4.0.1 to Use this plugin.

Meetings openfire is installed as a regular openfire any plugin: Log into the Openfire Admin Console, and navigate to the “plugins” tab. There, select the “Available Plugins” menu item, find the “Openfire Meetings” plugin in the list of available plugins, and press the install button.

Link https://github.com/igniterealtime/community-plugins/tree/master/ofmeet.

They have any idea if I need additional configurations to solve this problem?

Clarified that between the server where the application runs and pc from where we perform testing, no firewall acitvos, or iptables.

Functionalities Share documents, drawings and chat, work correctly.

Best regards