First of all, the DVD-ROM device needs to support DVD-R DL discs (DL stands for Dual Layer). If it doesn't have support for Dual Layer, the content will be burned to only a half of the disc. This is most likely the problem of yours. Getting a new DVD-R DL device might cost you additional money since this is a feature of the device, not something you can add while tweaking the writer with an application. After, you replace the device with a capable one, also adjust the quality of the video format to fit the DVD you're burning on. I recommend Amazon or NewEgg to buy a DVD-RW device with Double Layer support.