I've recently discovered that Amazon has movie (DVD/bluray) coupons in addition to their toy coupons and grocery coupons. I'll add this link to the main Amazon page so that it's always easy to find.
This month, it looks like all the coupons are for musicals. This is pretty great, because they're also on sale. The King and I is $18.49 and has a $3 coupon, bringing it down to $15. They also have coupons for The Sound of Music, South Pacific, Moulin Rouge, Rocky Horror Picture Show, and History of the World Part 1, among others. My favorite deal is $15 off (yes, FIFTEEN) The Sound of Music special edition.
Check out all the coupons here, and refreshing the page may help more coupons show up. If you click on the movies below, the coupon SHOULD already show up as being clipped for you.
There are also some great pre-order deals on Disney releases, so check these out as well.
Save $8 when you pre-order The Lion King Combo Pack with one of the eligible Disney Combo Packs listed below. This offer is valid through October 3, 2011. So, you'll need to pre-order The Lion King, then one other title--there are a lot of good options. Bambi, Beauty and the Beast, Dumbo, and many others. See all the details here.
Save $6 when you pre-order the new Pirates of the Caribbean movie On Stranger Tides along with one of the other movies in the series. Check that out here.