Thank you,
Indeed the reduced quality remains even when I view it on 1080 in Youtube.
I have tried to do two mp4 “Internet 1920×1080 30p” (under Sony AVC/MVC) – one default (16 000 bps), and one custom with 14 000 bps and “high”. I have added the three resulting images here:
https://tinypic.com/r/108hk5z/8
As you can see the render degrades quality a little while Youtube degrades it even more. However, Youtube is full of great videos of ture Full HD or even 4K. So perhaps I am doing something wrong?