Use 2X burn speed, and for movies, use -R blanks. -R is much more compatible with stereo DVD players. I found Maxell -R, 4X, a bright yellow DVD is the best. The 8X, -R(made n Central America, and a dull gold color) X are not as good as the Maxell -R, 4X(Japan).I have tried all kinds. Also good are Verbatim -R, 4X in the new 10 pack. All other Verbatim are not very good.
For data, most +R are quite good, and highest speed works fine. but avoid Mitsumi, +/- R.
TY CD blanks are very good, but I do not know anyone who has had good luck with TY DVD blanks for movies.
Overall there are many inferior brands of DVD blanks....especially house brands.