Backing up DVDs

[steelcmg]

So i have backed up a few movies that i have and have run all the test stuff that is in nero to make sure the burn worked. But i still get some of the movies that cannot play right. They still blip out and freeze up. I have no idea why they r doing this when nero says the burns are good. Im using some decent but not great Dvds (ridek dvd +R) I am lost on why they do this. The discs are clean and i do not see any scratches. Anyone have any ideas on whats causing this or what i can do to fix it. I have lowered my burn speeds and started making the files smaller by getting rid of stuff i dont need like extras and spanish audio.