[HELP/C#] How do I start playback of a stream (1 Viewer)

[Mavamaarten]

I'm a rather experienced C# coder, and I really really feel bad for making this thread.
I have made a Noobroom API for C# before, and now I was making a plugin for MediaPortal. Everything is working great so far:

Now the thing is, I cannot start the playback. I simply have no idea how! I have tried

MediaPortal.Player.IPlayer player = new MediaPortal.Player.PlayerFactory().Create("URL");
player.Play("URL");

But other than showing a little loading circle it does nothing at all. I have checked and the URL my API generates is correct and leads to a .flv file. Can anyone tell me how to start video playback or stream a video? I suspect it's easy but the documentation doesn't say anything about controlling MediaPortal functionality.