DVD file error- Workarounds?

I am trying to copy some files onto my hard drive from a DVD. They are high definition video files- when I play them from the DVD they play fine with no errors- but if I try to copy the files onto my hard drive it will not let me and I receive an error. There are 4 total files on the DVD, 2 copy fine but the other 2 won't.

Now to me- if the file plays fine from the DVD then I would think there must be a workaround since the file itself does not seem corrupt. I have tried the following:

- Dragging the file to destination
- Selecting Copy/Past to destination
- Booting into my windows partition and copying
- Attempting to Zip the file from the DVD and saving it to the hard drive.

Any other suggestions here? Any way to kind of rip the file off of the DVD as if I was doing it with a video DVD? (mactheripper type program?)

Also, are there any video programs that might allow me to open the file and save as another file (like quicktime does with other video files?)

Thank you for any help guys and gals!

You say they play fine with no errors, but have you played them all the way through? If neither Mac OS or Windows will let you copy the files, it can't be a software issue so the problem must be with the disc. There really aren't any tricks that will help you, aside from maybe cleaning or resurfacing the disc.