Hi,go to www.dvdfab.com and download the DVDFab Platinum for 30 days for free.It will drcrypt anymovie and then you can burn it.I used it for the Incredible Hulk Episodes of 4 per disc.It worked.
Use ImgBurn for your burning engine. Here is a LINK to a guide for using it. In the Write File Mode you can add all the files you want (that will fit on the disk) and burn them to your disk. Great burn engine and it is free.
If what you want is to make a datat DVD,for storage/transfer and such the above mentioned works.
otherwise, if you want to use those two segments and make a DVD compilation playable in a standalone player, you need to author a DVD.
You can use DVD Shrink and Re-Author a new DVD with the 2 titles. Or you can do that using CopnverxtoDVD for example(it is not free), or DVD Flick(will also create a menu if you care for one).
Since those are mpeg2 videos already, set DVD Flick so it would not re-encode.
For future reference (or you might choose to do the project again, you could've done this in a much simpler manner.
Since you use 4 different clips from the same DVD, all can be done in DVD Shrink.
What you have probably done is save the 4 clips one by one. All you have to do is open DVD Shrink and drag the movie in the Re-Authoring windows 4 times at once and use the cut function on each one to select your 4 video clips.
Now DVD Shrink would create a DVD with the 4 clips that you have edited.