To achieve this requires the skills not only to edit video from original DVDs but to edit multiple channel digital sound as well. Cuts have to be covered by smooth transitions, there should be no inconsistencies from one side of a cut to the next, and the final result should play with little or no difference in quality from the editing standards of the original.
It's quite a challenge to pull off, and you can see some of the best results here at the fanedit.org website. Fan edits are, of course, strictly illegal as they infringe on the original owners' and publishers' copyrights, so the site cannot host downloadable files itself. But the edits aren't intended for sale or to compete with the originals, and the site does tell visitors to be sure they've bought an original before downloading the fan-created version. It's hard to imagine the reputations or profits of movies being damaged by fan editing, but even so, be aware of the law in such matters if you do elect to download anything.