I went back and watched the original video in this post and noticed that the Smart Controller is actually over filling the screen on that Samsung TV. Didn’t notice that before.
I used the "smart view" screen casting on my Galaxy Tab S4 to a 55" smart TV over wifi (both tablet and TV on same wifi network).... then ran GO...
Lag was minimal and it worked a treat - great way to let a larger group see whats on the screen