I downloaded some files from our Panopto recording area using advice from here:
https://support.panopto.com/s/article/How-to-Download-Video-or-Audio-Streams-as-MP4s
This allows download of audio and video separately - I downloaded as MP4.
Camtasia couldn't generate any sound from the MP4 files.
This site told me to use Audacity to do this: https://support.techsmith.com/hc/en-us/community/posts/360071641332-Importing-MP3-audio-file-into-Camtasia-8-1
Audacity required the use of a library: https://manual.audacityteam.org/man/installing_ffmpeg_for_mac.html
This allowed export of a Wav file.
Camtasia can use the Wav file.
Took a while but all in all quite good.
