As I understand it, DVD-VIDEO backup is dependent on the SOFTWARE, not on the drive's "sheep rating".
The original "sheep rating" came from Elaboratebytes CloneCD, at the time when SafeDisk 2 upped the ante with weak sectors.
Originally, SD1 backup only required the ability to replicate errors.
SD2 introduced, amid confusion at the time, "weak sectors" - the name given to them as they seemed to be hard to write accurately.
Though "2 sheep" is only certain for SD2.51 second version, maybe SD2.6
With SD2.8, 2.9, 3.x - it gets confusing again, with conflicting reports - the EFM patterns are tougher still, but there may be other issues - the supposed correctness from the writer, may also be dependent on the reader.
So for DVD-Video backup, especially if the source media has already suffered a bit of useage degradation, you need a good reader - even if that has to be a different drive to the writer, and you may want a reading drive that is not riplocked, so it can rip at better than 2x speed