There is only one program at the moment that can decrypt Blu Ray movies. That is AnyDVD HD. You can download the free trial from www.slysoft.com but it is only good for 21 days, after which you’d have to buy it.
To burn the movie to another disk you would need a Blu Ray burner and blank blu ray media. Many Blu ray movies are very large, I think they average over 30 gb, so they won’t fit onto the 25gb blank BD-R or BD-RE disks without compression or trimming out unwanted extras. 50gb blank disks are available, but are still very expensive. Of course, if the movie happens to be one of those small enough to fit a 25gb blank disk, then you can do a straight transfer.
You can use ImgBurn in UDF 2.5 mode to burn blu ray movies.
If you want to select just the main movie and one audio track, you might be able to fit a movie onto a BD-R 25gb disk, but it depends on which movie you are trying to back up. You can use tsMuxer to select portions once the movie is decrypted, and then output as a blu ray disk.
You can also use a program called BD Rebuilder. It will compress the movie to fit onto a 25gb blank disk. It can also compress to fit onto dual layer or single layer blank dvds…but those disks won’t play in all Blu Ray players and the latest version’s output is causing playback problems in PS3’s when using blank dvds instead of blank BD-R disks.
You should also be aware that compressing high definition video takes a powerful computer and a great deal of time. My last attempt to compress a Blu Ray movie to a dual layer dvd size took 14 hours using a Core2Duo based machine.