This video best describes my problem.
Any Idea why this would happen? Only happens in 4th gear.

Transmission fluid was changed at 47000 miles. Bought the car used so i do not know if it was done before that. The car now has 53000 miles on it.

 

Looks like your SST transmission is slipping...

 

Uh oh, slipping in gear is never good, if you go to the dealer they will request you to change your SST oil and filter then go from there.