Yes, this is a very common "feature" on many modern displays. Virtually all "120Hz (240Hz, 480Hz)" LCD displays and even some plasma displays have this "smoothing" feature now. Samsung calls their version "Auto Motion Plus". The technical name for it is "frame interpolation".
The signal that comes from your cable/satellite or from your DVD player does so at a rate of 60 frames (or fields) per second. But a 120Hz display is refreshing its image at twice that rate. Rather than just show each frame twice, Auto Motion Plus (and any other frame interpolation processing with a name like "Motion Flow" or "TruMotion" or "Smooth Motion" or what have you) takes a look at one frame, takes a look at the next frame and then "makes up" a totally new frame of its own.
With Blu-ray, the effect is even more pronounced. Blu-ray delivers the original 24 frames: exactly the same as the original film. Rather than just showing each frame 5 times, Auto Motion Plus takes a look at one frame, takes a look at the next frame, and then "makes up" 4 whole new frames!
All of these "new" frames that never existed in the origin source end up making films and TV shows look odd and unnaturally "smooth". You might also get errors in the picture where the processing places an object slightly out of position creating momentary "blips" or multiple "ghost trails" of an object on screen.
Thankfully, you cab turn off this processing. Just go into the menus an find the Auto Motion Plus setting. Turn it to "off" and things will go back to moving the way they ought to! Do not worry, your TV will still be refreshing at 120Hz. It's just that, with Auto Motion Plus turned off, rather than "making up" new frames that shouldn't be there, it will just show each frame twice or 5 times as needed
