I've actually used ffmpeg + GNU screen to do something very similar in the past.

The benefit of using GNU screen is that the "tape" can be a shell script. I suppose if you don't like shell scripts that's not a benefit, but I do like them.

For example, instead of:

    Type "echo 'Welcome to VHS!'"
    # Pause for dramatic effect...
    Sleep 500ms
    Enter

With GNU screen, you would write:

    #!/bin/sh
    screen -d -m -S whatever -- bash
    screen -S whatever -X stuff "echo Welcome to screen" 
    sleep 0.5
    screen -S whatever -X stuff $'\n'

If you want to start interacting with the session, just do screen -r whatever

You can also read what is in the screen with -X hardcopy, then do something with the output, like verify the output is correct or adjust the input.