The VLC control for WPF is available and is the Open-Source code. Please see:
http://vlcdotnet.codeplex.com/[
^].
VLC certainly supports RTSP (if used as a client, which is all you need for now, and, with some effort, as an RTSP streaming service as well) and a lot of other things.
I would recommend using VLC rather then QuickTime. I have some problems with both, but, when VLC has matured, it worked for me well. The mere fact that QuickTime is a proprietary closed-source Apply thingy makes it risky; besides, it always looked ugly on Windows, as nearly everything Apple develops; from all I knew, Apple looks quite hostile for "foreign", non-Apple systems and platforms. Even Mono for Apple has the most of problems, comparing to good portability and smooth operation on Linux and other platforms.
—SA