Quite a while ago, I started a thread here describing how to customize the player to allow for text overlays:
I have created a plugin called Textmark that will allow you to do this without customizing the player code. This is not an official plugin yet. It still needs to get approved for the AddOns section, but in the mean time, you can get the plugin code that I've developed and find the options here:
http://totaldev.com/content/jw-player-textmark-plugin
This plugin will allow you to place multiple text overlays on top of a video wherever you want them. The page linked about contains the files needed and describes how to use it with the latest JW Player. I intend to get this approved as an official plugin, but for now, go there to grab the code and start using it.