When you put these unencrypted dvds in the dvd drive of your computer, does the name of the disk show up on the drive icon in My Computer?
Can you right click on the drive icon and hit Explore and see the contents of the disk? If so, you can just drag and drop the Video_TS folder to the hard drive and copy from that.
If you cannot do this, your disk may have corrupted slightly. Enough to cause problems for copying. You might be able to use ISOBuster to extract the contents of the disk.