I guess it varies depending on your viewers watch time. Let's say you have a one hour video with 4000 views, and all of that viewers watch your video from 0 to 60 minutes. So now you have 4000 watch hours. But if you have one hour video with 4000 views, and the all of those viewers only watch from 0-30 minutes, now you have 2000 watch hours. But I could be wrong tho.