I have been using DVD-r for 3 years now and have always understood that this medium is for one-only recording.
However, just to experiment, I tried erasing a DVD-r with about 20 minutes worth of material recorded on it. The disc came up completely blank, with a full 2hrs of time in SP mode. I have done this many times since, and discover I can erase up to around 30 minutes and salvage the entire disc. I use stand-alone Panasonic DMR E-30 for recording. This will not work with a computer DVD writer.
Just wanted to share that with others who have been frustrated by botched recording and have thrown away discs that may have been re-usable. Has anybody else run across this?
This one tip will help you sleep better tonight
A few seconds are all you need to get a better night's rest.