Here's your navigation clues:
$75 off $100 - 2 ways to get this: 1) A limited # of people were able to put in their mobile number to get text updates (bottom left where it says "Item of the week - get text updates in an orange bubble to the right of that"). 2) Click on the dog (top right picture) and he will bark once...a squirrel will then run across the picture w/the two girls (top left). Catch the squirrel and click on it (you have to be fast). You can only get it by clicking the squirrel the first time--otherwise refresh and try again.
$50 off $100 - Top picture, 2 girls, take the camera from the girl on right and move to middle top picture and place in woman's jean pocket(on right) - Click the picture and a picture will fall. Catch the picture for $50.
$10 off $50 - Click on the top right picture w/the couple. They will split apart (Josh & Kelly) and the $10/$50 will pop up.
$5 off $25 - in the video, about 1 minute in, click around till you find it!
25% off - Click on the sunflower (top left picture with 2 girls-it's on the bottom right)
15% off - Text update - put in your mobile number and the 15% will pop up (this is on the bottom left, where it says "Item of the Week"
10% off - Top picture, 2 girls - click on the girl's yellow headset
(Editor's note: I've noticed that the undisputed Queen of the Blogosphere for lightning-fast Old Navy updates is Thrifty Northwest Mom. And she's a sweetie!)