Requires an ffmpeg installation and python. Point the script to the public URL of a Big Blue Button recording and it will use ffmpeg to download the deskshare and webcam stream into a matroska file. For example:
./bbbget.py <my-fancy-bbb-server>/playback/presentation/2.0/playback.html?meetingId=2c213607ffefdb6fca039f176f132f35c7cc2a79-1589181959061 -o my-recording.mkv
Will create an mkv with both streams included.