I am using Ubuntu mate on my PC. I want to copy video from my hard disk to my PC. When I connect, I will get notification but when I search I am not able to find my hard disk folder. Please help me out.
Hi,
is it an external USB drive you are trying to connect?, it should auto mount and then open your home folder, all you need to do is look at the tree on the left of caja (your home folder) and click on the drive!. 
You will be asked how you want to handle the media when it is inserted, I always click on cancel and simply open my home folder and it appears on the left like the pic below:
