Mrsmadevans - I found your post really interesting! We give away a great deal about how we are feeling and what we are really thinking non verbally and i can absolutely see that, especially on a screen and while we're obsessing over what's said, these little signs would be missed.
Body language is fascinating and it's so easy to learn a few of the very basic little bits and pieces. As a total non professional i find it hard to concentrate on the convo. and properly clock the body language of who you're talking to mind you. One thing which is easy to try though is the physical mimic thing. If someone likes you or feels in tune with you they'll copy your physical movements while you chat. So; leaning while you talk, lean the other way, hand on a door frame, one hand across the body, crossing one foot over the other, resting chin on fist at the table, ect. I did it with the plasterer the other day and it worked and it was fun 
Anyway - as you were.