Probably rarely discussed, but I think there are only a handful of folks here at WW that actually use video judging by the activity. I'm trying to get a grasp on what's the best volume settings to use with video. This probably has more to do with each individual user.
For actual YouTube viewing I always keep the volume cranked to the max because most videos are not loud enough to begin with. I have no hearing difficulties.
PC settings I keep the volume at 50%. In the edit mode of Sony Vegas that I use it's usually set around 8 decibels for voice overs and other audio media unless the source is too loud or weak.