I have a new theory as to what is happening. I think you may have a newer version of MVTools than I have.
I used mvtools 1.9.2 you used mvtools 1.9.3. I've tried both and learned that it makes no difference.
I started to encode the scene I posted with screenshots further again, to be sure, I have not used a wrong plugin.
So I downloaded the plugins as you postet for download earlier here. The result was the same.