I DVD

iDVD doesn't care about size/capacity of the DVD disk. It's only concern is the total playing time of all the media including menus.

A single layer DVD-R can hold up to 120 minutes of total playing time.

A double layer DVD-R can hole up to 240 minutes.

Also where are you seeing this 7.8. GB? If it via the Finder for an empty DVD-DL?

Note: using all caps is tantamount to shouting in forums and is harder to read. Please kuser lower case and sentences with correct punctuation.

Go to the Project ➙ Project Info menu option

and in the Project Info window select Double-Layer in the DVD Type menu.

Follow this workflow to help assure the best qualty video DVD:

Once you have the project as you want it save it as a disk image via the File ➙ Save as Disk Image menu option. This will separate the encoding process from the burn process.

To check the encoding mount the disk image, launch DVD Player and play it. If it plays OK with DVD Player the encoding is good.

Then burn to disk with Disk Utility or Toast at the slowest speed available (2x-4x) to assure the best burn quality. Always use top quality media: Verbatim, Maxell or Taiyo Yuden DVD-R are the most recommended in these forums.

If you need more help you know where to find us. 🙂