Those video things are confusing for many people, don't worry
Look, what you usually call "smooth" is the video footage like an NBA game
shot on video which is interlaced, so you have 50 fields per second (in PAL)
- 2 fields per frame - not 25 progressive frames per second.
It's two times "smoother" than a Hollywood movie transferred from cinema 24fps.
For many people that jittery look is what makes it look like a movie and not video.
There is no practical difference in perception between 24fps and 25fps.
There are several PAL "tricks" to display a 24fps movie on a PAL device in 25fps
in a PAL country. And it's not easy.
But it's very hard to convert 25fps to 24 fps.
You need to loose a frame per sec, so you have a jump. You can't perform
a speed change because you destroy the quality of the perfect frames.
There are some algorithms generating "new" frames, but they all degrade the quality.
Plus you have a big audio issue.
K-5 is clearly made for PAL countries.
It's just seems easy enough to shoot 24fps if your hardware allows 25fps.
Not sure what the problem is.
When Canon 5D II was released with 30fps only, it was a huge revolution
which finally made Canon introduce the fw with 24fps. It was possible.
We'll see...