Thumbnails from DVDs

Why is this kind of software not more common? Been looking for years and never finding anything perfect. Image Grabber II works at least. I have my own DVDs with my own footage and I just want something to go through the DVD video and pull thumbnails so I can make decent covers for them. This software work pretty damn good but you have to open each .vob file and grab thumbs individually. You'll have fun renaming them if you want to keep them in order after going through multiple .vob files.