at the end what you taught was kind of confusing.... Interlaced scanning and non interlaced scanning were both explained together and in the non interlaced scanning part you just told the frame rates of both the scanning techniques
true, moreover in this video she says raster scan is more expensive yet in the difference between random and raster scan video she says raster scan is less expensive.
In my opinion what u r teaching is wrong about that on/off it gets off only when the beam moves from left to right(next line) as whenever electron beam is present on scan line (starting point top left) then it stays on so what u r teaching is wrong it will make pple confused