Usually when the program glitches at 98%, it's an indication that it can successfully transcode a DVD, but that things are fouling when it tries to burn it to your disc.
The wisest solution is to select the option to burn your DVD to a Folder on your hard drive rather than directly to a disc. This will produce your DVD files. Then use a program like the excellent ImgBurn to burn the VIDEO_TS folder to a disc.
There are many advantages to doing it this way (I cover them in my book on Amazon, if you're interested). But it will certainly fix your error issue.
Downloading means transferring files from the internet to your pc.
50 short videos on one timeline; make sure there are no gaps and no end marker.
Can you make a folder or iso?