Unfortunately, the root application of the web service under which Red5 runs belongs to the http-bind BOSH service, so RTMPT is not supported out of the box.
If you really need it, then you can manually move Red5 to the root web application. The location is OPENFIRE_HOME\resources\spank.
The alternative is to spawn a new jetty web service on another port like 5080 instead of using the http-bind web service on 7070. That will will require a bit of coding