Lots use RTSP and others use RTP.
One way to solve it, if you're determined, is to install
Wowza and reflect the streams. Wowza allows you to receive incoming streams from a wide variety of sources and reflect them in almost any format you can imagine, including RTMP (Flash), HTTP Live Streaming (Apple), and SmoothStream (Microsoft/Silverlight). It can make it into a streaming format that MC can receive and play.
It isn't free, but it works awesome. There is a free trial, though. If you want to do it, they do still have a perpetually licensed version you can host yourself. The trial might be enough (it isn't time limited, it limits the streams you can receive and send).
There is also Red5, which is an open source project that basically tries to do the same thing. Last I looked, Red5 was VERY difficult to set up and configure, and was limited in the types of things it could handle (plus, documentation and support was pretty much non-existent). But, last I looked was a LONG time ago, because I use Wowza.