can I burn a 720x1280 video on a dual dvd? It's a HD video

Short answer: No.

You cannot author and burn a DVD that is any size other than SD (720x480 for NTSC).

You can burn a file on a DVD that is any size you want, but it will not play in a DVD or Blu-ray player.

You can author a small Blu-ray project in Encore, build it to a Blu-ray image, and burn that image to a DVD, but it must play in a Blu-ray player. It is not a "DVD." And will not play correctly in many Blu-ray players.