I heard that you can increase your DPS depending on how you attack.
I found this video from the beta. Does this still work and what has the highest DPS?
It appears you are referring to the phenomenon of getting different attack speeds based on whether you hold down the mouse button to attack, or click repeatedly.
Community Rep Bashiok confirmed that this would be fixed:
Right now you can get a higher damage output, for example with the demonhunter, by using shiftclick or just spamming leftclicks on the mobs.
The attackrate is slightly faster when using shift or just spamming abilities because you can cancel the full attack animation into a second and third and so on. Therefore it does the highest DPS to spamattack.
As Wikwocket stated it'll be fixed and my guess it's because they don't want the casuals to be excluded from doing more damage because of such a silly bug. It also looks stupid so there is no reason to keep it in.