Is it possible to master a DVD with 720HD high-definition video?
No, there is simply no way to encode HD resolution video onto a DVD. This is a common misconception. The DVD video format does not support HD resolution. DVD players cannot reproduce 720HD video.

If you want HD on a disk, that is what Blu-ray disks and Blu-ray console players are for.

There was once a format called HD-DVD, but it is no longer supported by anybody and standard DVD players will not play back an HD-DVD at the intended resolution.

720HD is 1280 x 720 pixels per frame.

The highest resolution that the DVD format can support is 720 x 480 pixels per frame for NTSC (or 720 x 576 pixels per frame for PAL), which is at best only 37.5% of the resolution of 720HD.