You are confusing strobe-like flashing with frame rate. TVs typically display a frame rate of 24fps, but actually flash at a much higher frequency (anything from 50Hz, to 960Hz on newer plasma TVs). Some TVs/monitors actually flash each line one at a time (interlaced scanning), some flash the entire image at once (progressive scanning).
The Hobbit was filmed at 48fps instead of 24, but this has nothing to do with flashing - this is simply the frame rate (ie the still image changes 48 times per second). The actual refresh rate would depend on the projector used. It does look different, many newer TVs have a "100Hz" refresh rate which basically gives the same effect - The picture looks a lot smoother when there is fast movement on the screen. Personally I don't like the effect, I prefer the standard 24fps (it can look flickery when there is movement, but I think it just looks better).
As someone said upthread, the "hypnosis" is all to do with the CONTENT, and nothing to do with any brain entrainment or hypnotic flashing.
Don't get me wrong, I think TV these days is fucking mind numbing, it's all made to cater for our ever decreasing attention span. I think this is partly to do with there being so many competing channels/media portals, all vying for our attention. Attention = viewers = advertising revenue. It's all as simple as that, we seem to be stupid enough to fall for it without any hypnotic technology being involved.
I am not confusing anything. Frame rate = flashing still pictures at XXhz. The overall flashing varies depending on, as you mentioned, film frame rate as well as the actual viewing device used and its refresh rate. Regardless of the hz rate of a monitor you look at, the predominant visually perceived rate of the frame/flashing is dependent upon the video format settings. In short, even if your refresh rate is 70hz, the visually predominant effect will still be the frame rate, because the screen is often refreshed as you said one pixel line at a time. Additionally the higher the frequency, the less able the human eye is able to perceive it as an independent "frame" or flash if you will. At a certain point the human eye simply can not perceive them as independent frames any longer, physiologically reducing the perceptive effect of entrainment.