some of the rides now include a video...Tower of Terror is one...includes a ride intro and then some quick cuts of your ride experience...on top of the ride photos as well.
Is MM worth it? It can be...but you have to make it worth it. You have to stop and get photos taken in the parks, I wouldn't buy it if you only want ride photos.
The download cost without MM is $14.99...so if you plan on getting 11 or more photos, then it is worth it...but if you always walk past the Photopass people and don't get photos, then there aren't enough rides with photos to get your money's worth.
We always get it, but then we tend to get as many photos in the parks as we can.