While shooting whenever i change the shutter speed to 1/250 in 25p, i can see a dip and dim lighting effect in the video, what the thing im doing wrong, when i shoot it in 1/60, 1/50 im not geeting any trouble.
You're saying that when you are in faster shutter speeds, the camera doesn't perform as well in low light?
1/24 requires less light than 1/250. 1/60 requires more light than 1/24, etc, etc, etc. Longer exposure means more light sensitivity. Shorter exposure means less light sensitivity.