WM Recorder is a recommended stream recording software. But it is not an ultimate stream recorder. As any other stream recording software it can't record all streams formats available.

Most streams can be captured with WM Recorder + Replay Media Catcher.

liveprivates.com offers RTMP flash .FLV video streams (at least for free adult video chats). Please read the following guide to learn how to capture them:
How to record/download/capture/save Macromedia/Adobe Flash .FLV video RTMP stream from embedded player

Although I like Replay Media Catcher more than any other flash RTMP recorder, for web-sites like this it is better to use FLV Recorder.

Replay Media Catcher creates a separate downloading thread and you can be detected because you can't click onto the Pause button in a video chat. And FLV Recorder just captures packets coming to your PC.