Tearing is nothing to do with the screen, it's just what happens when the framebuffer is written to while it's being sent to the display. Well if you want to get really technical about it it's when the pointer to the framebuffer and backbuffer are switched while the video card is sending a frame to the monitor. The only way to get rid of tearing is turning on v-sync, but of course you can't turn on v-sync for the desktop, only for full screen apps, so any movie player that plays movies onto the desktop can potentially suffer from tearing.
Look in the setting in your movie player and see if it has any alternative output methods (like overlay, d3d etc, hopefully one of them will be synched), and if that doesn't help try a different movie player. What movie player are you using btw?
If you still need convincing, run a full screen game with v-sync on, which will of course produce zero tearing, and then tell me how the tearing during movies could be down to a faulty screen.
