Using one of these screencaps as your sidebar picture is perfectly OK, as long as you give credit. Using one of them as your icon is also OK, no credit needed. (Though I would appreciate if you let me know!)

I have taken most of these caps myself. The rest are from homeofthenuttyfishsticktheatre and grande-caps

I make my caps with KMPlayer. I edit everything with Photoshop CS4 / CS6.