now in my opinion you should keep it normal for some music/videos or you can use the 1.5 speed option.
with the 1.5 option you can hear it clearly its just sped up and it sounds pretty cool. if you set it to 2x speed then you can understand it but some bits of talking or music is left out.
if you set it to 1/2 you can hear it a bit but its just slowed down. with the 1/4 option you cant really hear anything its bad but slow motion for if you miss something.
i have also noticed that it only works for certain videos whether the videos have to have copyright free music or no using anyones game i am not sure but it is for certain videos.
thanks for reeding and have a nice day :)