Regarding your question about DVD. It is a little confusing. The positive one is the 1st release version. During the 1st release burner, old DVD only reads positive only. But the later version now can read both positive and negative. But Using definite sign on burnnig will depends on what kind of burning style you will use. whenever it is data file or dvd format video. If you burn video with DVD format video, negative sign is advisable, this include media file like audio and file video. If pure data file like document files, use positive sign. I won't explain more the technical stuff how burner writes on positive and negative sign. Now a days, negative sign is much easier to write.