You do need to make sure you are running 4.1.0 at least for this to work. An example implementation would be
You will need to pull apart the request and headers to see what is being requested. You can also use the IVHostHTTPStreamerRequestValidator interface and a quick google did find some examples of implementing this.
public void onHTTPSmoothStreamingStreamerRequest(HTTPStreamerSessionSmoothStreamer httpSession, HTTPStreamerSmoothStreamingRequestContext reqContext)
IHTTPRequest req = reqContext.getRequest();
Map<String, String> map = req.getHeaderMap();
// if the request is missing “my favorite header, reject the session
if (!map.containsKey("my favorite header"))