Hello, so ran by your post when searching for the same thing. I couldn't open my video with multiple tracks in Camstasia, but was able to cycle through them with VLC player. What I did was used handbrake. In there I was able to select the video and which of the 2 audios that I wanted to export it with. I exported 2 versions of the video... each with a different audio track. So now I have 2 videos... 1 with my desktop audio and 1 with my mic audio. I can now edit as I see fit. It's a real shame that this can't all be accomplished within camstasia.
So Three years later and people still recommending to use the VLC and Audacity for this absence feature. Any chance this could be added in the near future? After making videos for about a year on youtube Camtasia does not have the ability to add filters to my mic while recording like a noise gate or noise suppression, which is why I use streamlabs OBS to record, not the CAM but I have recently started adding tracks to my recordings and having to use another program just to import and edit select audio like the discord from the people I am recording with. This has got old real old real fast and takes a lot of time. I really want to upgrade but unfortunately, I am looking for editing software that has the ability to at least see all my audio streams independently and save me what little time I have editing. I will keep checking in if I don't find something else that saves me time. Don't get me wrong I love all the little neat things you can do in CAM but a time saver like that is what a lot of people are looking for.