Have you considered the fact that perhaps the message you're getting is telling you the truth and that there's nothing more to add?
You're trying to import and work on full HD video on a three year old laptop and the software is telling you that your computer is not good enough and the image quality may be downgraded.
Your problem is that the "image shows blocky shadows or downgraded video", which is exactly what you've been told by the software.
So the way I see it, you've described the symptoms and the reason perfectly, there is nothing more to add apart from "buy a new computer" and as you've posted about four threads asking for advice on new systems, I reckon it's about time you did it![]()
