What is the best way to clean my MBP Retina screen?

I purchased a product called Whoosh! at the Apple store and was told it was the only safe product Apple recommends to clean retina screens. The weird thing is that Whoosh isn't sold at Apple store anymore and I'm wondering if it's because of the residue/streaks/film I'm seeing when I use it?

http://imgur.com/dWqtPvM