First off, if you're video is in one format and your TV is another(IE pal/NTSC) you won't just get a flicker. More like a jumbled picture, jumping, usally in black and white if you manage to get anything...
From the sound of it, you have your flicker filter off. Computer don't run interlaced, as TV's do. Computer also run at much higher resolutions that a TV. Usally you can adjust your flicker filter settings in advanced display proporties, but realize it's not really going to help with your quality. Maybe for text(not that it's very readable either way...) but videos typically look best when the flicker filter is disable.