Correct and Correct. I thought it wouldnt work either but it does... and its due to the Hard Disk Buffer (not to be confused with the onboard 2mb drive cache).
Ive got the HDD buffer in nero set to something large, 80MB i think, so at the start of the copying process its only the dvd reading for a little while, then when the buffer is full, the burner starts up.
So as the two drives progress through the medium, both increase in speed as you would expect, but you have to remember that the dvd drive is allways 80mb infront, and thus is considerably faster than the burner at all times.
By the time the burner has exceeded 48x and can catch up its too late as the dvd has usually stopped reading cauz its reached the end of the media.
Ive done around a dozen "on-the-flys" and ive only once seen the buffer dip below 97%, and that was with a badly scratched CD.
So it works, and works well. around 3:15 IIRC for a drive to drive copy. (taking into account the extra time needed to copy to the HDD buffer)
<b><i>The Very Hungry Caterpillar</i> - George W. Bush's favorite childhood book.
Note: This book was first published a year after Mr Bush graduated from College.</b>