51 Exercises - Flour Sack Falling (Looped)

My next exercise from the 51 Great Animation Exercises is the Flour Sack Falling.


I'm experimenting with a few things in this. The first is mixing the use of 1's and 2's on the same object. The main body of the bag is on 2's while the corners are on 1's to show them flapping in the wind as the bag falls.
The second experiment is the speed lines in the background. I've never done a quick looping effect like that before. I think I still need some practice with it, but I'm impatient and want to get this up.