Just saw this. Looks like the $1 Instant Video credit is over and now they are giving you $5.99 off a Prime Pantry box (basically makes the Pantry box ship for free).
Here's more info:
Looks like you can only use one $5.99 credit per order, and credit expires May 31, 2015.
No-Rush Shipping Terms & Conditions
- If you received your credit from the No-Rush Shipping program on or before March 24, 2015, different terms apply.
- Offer expires at 11:59 p.m. PT May 31, 2015.
- Offer redemption requires customers to be in the U.S.
- Offer only applies to Prime Pantry orders.
- A maximum of $5.99 per Prime Pantry order can be redeemed from this Offer.
- This is a shipping offer related to your Prime subscription; it is not a discount on items purchased.
- Amazon reserves the right to modify or cancel the offer at any time.
- Offer is non-transferable and may not be resold.
- If any of the products or content related to this offer are returned, your refund will equal the amount you paid for the product or content, subject to applicable refund policies.
- If you violate any of these terms, the offer will be invalid.
- Unless an Amazon Gift Card is the stated benefit of the promotion, promotional codes (including those placed directly in accounts) may not be redeemed for Amazon Gift Cards.