Well, this is a very interesting question. In fact, as a rule, it should be possible to create a live stream, but - and this is a “difficult” moment: you have to do it yourself, so you need to take care of everything you need for a real broadcast.
In detail, this does not greatly complicate the implementation of a kind of live stream. Think what you need:
1a) Image source (usually, of course, a cam) 1b) copier view 2) Streaming-Server 3) Streaming-Client
So, if we talk about Windows Phone, you have many .NET classes available that do some work for you. For a good start, you should consider the following link: http://msdn.microsoft.com/en-us/library/ff637518%28VS.92%29.aspx
If we move on to the details, you need to complete the following tasks:
1) Get an image of your camera
2) Copy the contents of your brush / canvas ui-element to the stream
3) write the stream to a temporary file
4) upload a temporary file on the server to clients
5) go into the loop and start with 3.
In this case, the big deal is to make a copy of the video brush, so for this take a look at the msdn link for the video brush
http://msdn.microsoft.com/en-us/library/cc189009%28VS.95%29.aspx
To have a good starting point for copying the contents of a video brush into a stream, review this document
http://msdn.microsoft.com/en-us/library/bb404773.aspx#anchor_videobrush_relationship
using the multimedia element as the host for live images.
Another, better, but, of course, more complicated way is to implement your own version of the brush. Read this article to learn how to copy the preview buffer.
http://msdn.microsoft.com/en-us/library/microsoft.devices.photocamera.getpreviewbufferycbcr%28VS.92%29.aspx
So, I hope I was able to give you an idea of how to implement my decision.
ps: If you can speak German, I recommend you a book: http://amzn.to/wxfEzd
I am the author of this book;)