Hi ayouh,
It sounds like you are having a video issue with your iPhone, which I am sure is frustrating. I do have some steps that may help you.
I would suggest troubleshooting using the steps in this article -
iPhone: Hardware troubleshooting
http://support.apple.com/kb/TS2802
Specifically -
Display image issues
This can include bright or dark pixels, lines in video, or sections of video missing.
- Try turning iPhone off and then on again.
- Verify the issue is not content related, by viewing different content.
- If the image is too dark, adjust the brightness. In General Settings choose Brightness and Wallpaper and slide the slider.
Thanks for using Apple Support Communities.
Best,
Brett L