Does anyone know why my facetime freezes when connected and recording videos back facing freezes and half screen turns green, audio works fine for both iphone5?

Hello everyone! I had a black iPhone 5 when they first came out and then somebody stole my phone. So I purchased a brand new white iPhone 5 brand new out of the box 6 months ago at At&t. When I first got home, and added all my contacts my niece tried to facetime my husband on my phone, well everything worked fine, up until we were connected and then the screen just froze but she heard me just fine. I was able to use Skype or any other app that you could video chat and the camera worked fine. Has this happened to anyone? All my settings on facetime are at where they should be.

And also, when I record videos through the back, and it saves to my phone and I go to review the video, the left half of the screen turns green and then my video freezes and then the right half you can see partial of the video but it consistently freezes and up and is slow. But then again audio works just fine. I can take pictures just fine and recording up front works just fine.

I have already done a hard reset and then did a DFU reset. Neither one of these solved the issue. I have been to the genius bar twice and told me that the DFU reset would work. But when I purchased the phone, I was not told about apple care at the time of the purchased. So I do not have apple care. If someone can help me, or have any suggestions, please let me know.