Most commercial dvds are too large to fit onto a single layer dvd without compression or deleting parts, like foreign language streams, commentary or extras.
If you made these ISO’s and video dvds yourself, you should be aware of the amount of compression used (if any). Excessive compression from a program like DVDShrink can cause artifacts and blockiness, but rarely skipping or freezing problems. Those are usually related to the media or excessive speed in burning. If you are burning these TDK disks at full speed, I would advise slowing down…8x or 12x at most.
By the way, there have been many discussions in the Blank Media forum about the poor quality disks that TDK has been marketing. They aren’t producing their own media anymore (unless in very small amounts only in Japan), so they are buying mediocre grade disks from Taiwanese suppliers.