Clifton's Lightbox implements a lightbox subscription form overlay. Features a title, list, call-to-action, and image or video.
First, check if the lightbox is Enabled. This is different than Activated. After you've activated the plugin, you will need to set up the plugin at Settings > Lightbox. Once the plugin is setup, you can Enable it.
If you still don't see the lightbox, perhaps you've already set the cookie. Go to Settings > Lightbox and click on the Delete Cookie button. That will delete the cookie preventing the lightbox from appearing.
In theory, it should work with any email marketing service. I've tested the plugin with GetResponse, Aweber, iContact, MailChimp, and others. The plugin requires the form markup to contain Name and Email fields.
Yes, you can set your own image or use a video from YouTube. Videos are a great way to deliver your message to visitors.