I purchased a Radeon HD5450 graphics card to check if it was the problem with the graphics. I used the same DVI-HDMI cable and found that, the same issue was still there, all greenish! Later on I tried with a HDMI-HDMI cable which worked! So I guess, that DVI-HDMI cable couldnt support playing videos as 1920x1080 resolution. Now no greenish color or pixelation!