I'm not really familiar with that piece of software. I used ConvertXToDVD to author my DVD, and didn't have any problems.
If you'd like to try out a commercial package to see if it work, Giveaway Of The Day is giving away free downloads of
ZC MPEG to DVD Burner, which can convert MPEG/MPG/Mpeg4/Mp4/VCD/SVCD files and burn them to DVD. This is a fully registered copy of the program, but you have to download and install it today - May, 19, 2008.
http://www.giveawayoftheday.com/zc-mpeg-to-dvd-burner/EDIT: I tried out the software, and it seem to work as advertised, though I encountered a few glitches. I had to enter the registration code twice. The first time didn't seem to work, as the software is limited to only 3 uses without registration. I had to quit, restart, and go through the registation a second time before the program seemed to be fully registered. The registration name and code is given to you when you install the program, but it's also in the readme.txt file in the ZIP file you download.
When selecting files to include on the DVD, the option "All supported video media format" doesn't seem to show all file types. Change the type to MPEG and you'll be able to see MP4 files.
The program has the option to burn the DVD for you without any other software needed. A great option for novices, but there doesn't seem to be a verify option. You might want to uncheck the Burn DVD option, and burn the DVD yourself with a program that will verify the burn, such as Nero, Roxio, or the freeware IMGBurn.
My biggest gripe with the program is that it doesn't generate a menu. For this reason, I think I'll stick with ConvertXToDVD for any simple conversions I need to do. But for a free program (assuming you download it today) to convert MP4 to an authored DVD, it'll get the job done.
I spot checked my test conversion of WEAT, and there don't appear to be any sync problems. I did notice that this program reads the frame rate as 24.39 frames per second, which is an oddball frame rate. I think this file may actually be a stream-grab from the streaming version of the episode, so there may be some dropped frames here and there, and perhaps DVD Flick can't compensate for it that.