The manufacturer will say: No full speed with DVD-Video because of the noise, nobody want noisy drives while playing Video
The community say: DVD-drives-manufacturer want to annoy us and decrease the speed to prevent mass-copies (if you need long time you mabe don´t do that)
It´s your decision want you believe
However, 12x speed is not quiet.
DVD-Video uses UDF-format, DVD-ROM use iso or also UDF