Hi,
Perhaps you can check out the manual to see how to change the video resolution or audio bitrate to allow longer recording.
(Refer to
http://www.dvd-guides.com/content/view/16/59/)When u use DVDShrink, at 1 click on DVD_Video and at 2 instead of leaving it at automatic, choose custom, use the slider and lower the size till about 2 GB+ or 4.5/x where x = the number of DVDs you wish to put on one DVD. But remember when shrinking a DVD, quality drops.
This is an optional Step. Burn it on a DVD-RW/+RW and see the results before finalising it to a DVD-R