Jaksta (editor's choice) can download and capture packets coming to your Adobe Flash Player. To download or capture RTMP streams with Jaksta:

• Run Jaksta
• Click the Record button
• Navigate to a web page with your video stream and play it in the embedded flash player.
• All .FLV flash video streams broadcasted through the HTTP or RTMP protocol will be downloaded/captured automatically.

Please note that when Jaksta captures packets from flash player (rather than downloads RTMP streams), you need to play an audio/video stream fully to capture it.