The third party ASTERIX CAT240 radar video viewer can only provide recording capability if it is specifically licensed.
https://cambridgepixel.com/products/display-applications/radarview-240-asterix-cat-240-viewer/
Recordings made with this tool are proprietary and can only be used with radar data processing and display applications from the company Cambridge Pixel.
An alternate way to record ASTERIX CAT240 radar video in a way that can be replayed in to any ASTERIX data consumer is to capture network traffic.
Part of the WireShark network capture tools, the command line application dumpcap can be used
https://www.wireshark.org/docs/man-pages/dumpcap.html
The screenshots and syntax below apply to running dumpcap on a Microsoft Windows platform.
First issue the command dumpcap -D to display a list of the network adapters
Ensure that the radar is configured to provide an ASTERIX CAT240 output and make a note of the configured address as shown in the radar web user interface screenshot below:
Launch the dumpcap executable as shown below, using the -f argument to define the destination of data packets to be logged. Use the -i argument to specify the network adapter in use for the radar’s connection, and use the -w argument to set the file path of the recorded data.
Recorded pcap format files can be inspected using the Wireshark application. Wireshark does provide some support to dismantle ASTERIX formatted packets in to their constituent parts (info here)
PCAP files can be played back as a network stream with a packet replay tool such as this one.