Hood and fender shake

I just bought these tires and don't have 500 miles on them. They were an improvement over the others that I had but what I can't figure out is why did the shake go away on a different stretch of highway and then return all the way home no matter what direction I went on my way home. If the lower control arm bushings are bad, what does the car do? Please look at the you tube video under Dart tire shake just to ease my mind.