So NBN plays Hot Seat off a clean feed with no pop-ups and their own bugs/graphics.
I think they do this to avoid any in-program crawls that may go to air for Nine News on the dirty feed (though when I watched on Monday there were no news crawls on Nine).
I also think they play the program off their own servers rather than off a Nine feed because I saw most segments going to air at different times (slightly earlier) on NBN compared to Nine.
Here’s some side-by-side comparisons of Nine and NBN at times showing different/missing graphics:
