Because DVD movies are parted into several huge files... Is there a program that can deal with that automatically? If not, I can convert them into AVI. Is there software to join videos together?
I decrypted a bunch of movies with DVD Decrypter, which have left me with multiples of .vob, .bup and .ifo files. The movies play fine on my computer, but I want to just convert (I'm not sure if that's the right word) all of the files into one .avi of .mpg file. I'm trying to explain this the best way that I can. I do not have the original copies of the movies anymore so I can not redo the whole process either.
Please help me!
It's so easy if you use some all-in-one DVD ripping software. It helps you rip DVD movies and convert to any popular video formats into 1 single video file.
If you're a Mac OS user, you need a DVD ripping software for Mac OS to rip/convert a DVD movie to 1 single AVI/MP4 video file. We strongly recommenda DVD ripper tool called iFunia DVD Ripper for Mac. It's really easy to use yet powerful enough to finish this work for all skill levels, even newbie of Mac OS.

Step 1: Download & install iFunia DVD Ripper software for Mac
We’ll be using a very nice DVD Ripping tool for Mac OS called iFunia DVD Ripper ( Mac OS only ) for ripping DVD movie into 1 single file, head over here and download the free trial version.

Step 2: Run iFunia DVD Ripper for Mac
Now get your DVD disc and insert it. Then run iFunia DVD Ripper on your Mac and click the big button "Load..." to load your DVD disk, you may see the name of DVD Movie disk if you insert DVD disk before running this DVD ripper tool. This may take up to a minute or two depending on the contents of the DVD and the speed of your optical drive.
Step 3: Select the titles you'd like to convert
A movie DVD usually has several titles. The shorter titles on the DVD are usually the video backgrounds used in the DVD menu screens and DVD extras like movie trailers. Unless you are a graphic artist, you probably don't want to convert these titles.

Step 4: Change the output settings to make the video look the best
There are almost all common video formats available for you to choose to convert to. You may convert DVD movie to different video formats for video editing or playback on your mobile devide, such as iPod, iPhone, PSP, cellphone, etc. The best solution for DVD movie backup would be to compress it to progressive lossy formats like Xvid.
Here I set the output video format to 'AVI - Audio-Video Interlace (*.avi)', Video Codec as 'XviD', Resolution as '680*480', Bitrate as '768', Frame Rate as '30', Audio Codec as 'AAC' by default. Remember that the output file size mostly depends on the Bitrate you set. Larger Bitrate, larger file size. Actually video with bitrate as 768 is acceptable for watching on computer.
Step 5: Start converting DVD movies into 1 single AVI/MP4 file
Now you may click the big button "Start" to begin ripping DVD movies into 1 single AVI/MP4 video file. The Convert progress bar shows you how much of the convert process is completed. The longer your movie and the larger its Bitrate, the longer the convert will take. The ripping time will depend on several variables including: the duration of the video file, the speed of your computer, what other activity your computer is currently doing, the codec you selected and the bitrate you set.
Once the convert is complete, iFunia DVD Ripper will place on your Desktop a new AVI/MP4 format version. Double-click the new file and play it to make sure it looks as you expect.
DVD Ripper for Mac is a professional DVD ripping software. It helps you convert DVD content to any common video formats for playback on media players and mobile devices. You may rip a DVD movie to 1 single AVI/MP4 video file to get a compromise between file size & video quality.

(PC user? Get Windows version here)