You've used the wrong type of DL media. We do not recommend Memorex media, especially their DL disks.
I suggest using Verbatim brand DL disks, and burn the dvd-video with ImgBurn, since it will set the layer break correctly. ImgBurn is a free burning program found here: www.imgburn.com
Burn at 4x speed, regardless of whether you get the 2.4x-6x or 8x variety of Verbatim DL +R disks.
Does the converted video play properly from the hard drive before burning? If you haven't done so, test with your normal software for playing dvds...like PowerDVD, WinDVD, or a free player like VLC.