It depends on the offer you get and how often you really buy dvds. We buy a lot of dvds, especially disney and I joined a year ago. The offer we got was $1 a movie plus free shipping for the first 4 and 2 additional movies at $14.95 (counted towards commitment) and $9.99 (didn't count).
Then I added up the cost of those, plus the cost of 3 more at $21.00 +$3.95 shipping and divided it by the # of dvds I would get in total and it came out to $11 a movie. It was worth it to me for that. I don't think I will continue to buy any after I buy one more to meet my commitment unless some really good special deals come along after that.
Shipping goes down with each additional movie ordered to I think $1.99? (like you buy 2 1 is $3.95 and 2 is $1.99 in the same shipment) and sale items don't count towards commitment.
While it says dvds $19.99 and higher count towards commitment I've found either they are on sale or they are $21-$22 plus shipping.
Good luck.