WordPress.org

1. Go to Plugins -> Add new in your Wordpress Admin
2. Search for bubblecast, click Install, then Activate
3. Enter you bubblecast login and password at Settings -> Bubblecast and click Save and Login.

WordPress MU Users only. Copy mu/sitewide_bubblecat_video_plugin.php from Bubblecast plugin directory to wp-content/mu-plugins. Don't forget to grant read permission to your web server to this file. For example on Linux I use chmod 644 sitewide_bubblecat-video-plugin_video_plugin.php

Manual installation described here Bubblecast video plugin for Wordpress