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Re: DVD Double Layer Playing problem

I recently obtained a two DVD+-RW DL burners and decided to test them by
trying to burn a copy of Monster's Inc (which is a DVD we own that is a
DL disk)  They are the Plextor DVDR PX-750A  and the DVD-RW drive that
comes with the SONY VIAO VGN-SZ160P.

I used
dd if=/dev/dvd of=DVD.iso bs=2048

to make the ISO, and

growisofs -dvd-compat -Z /dev/dvd=DVD.iso

to burn it.
There were no reported errors at all during the burning process.

I can mount the burned disks on the either of the Dl DVD+-RW drives that
did burning, but my oldest DVD drive (which is only a DVD-RW single
layer burner) thinks there is no media there (it can play commerical DL
DVDs just fine).

It's probably deficiency of this recorder. Recorders [unlike pure ROM players] are expected to have closer look at media, closer than looking at Media Book Type that is. It probably smells recordable media, but it's too old to believe that it's double layer...

 I can play the ISO image with xine no problem and I
have used "diff" to verify that
1) The ISO and the burned DVDs movie are the same

But I cannot play the burned DVDs as video anywhere, including the
drives that burned it one (with either windows or linux)  On windows or
a commercial stand-alone DVD player I get a frozen scene from one of the
previews with a stuttering text that loops after a few minutes.  With
either xine or totem it reports that this DVD is encrypted and
recommends that I install libdvdcss.  I have libdvdccs installed and it
is what I use to watch most commercial DVDs that I watch.

Content protection is two-fold. First you have to authenticate yourself to unit so that it gives up protected sectors, and then you have to descramble the content. When you ran dd you probably were authenticated [you probably ran xine prior dd], but dd doesn't do any descrambling and therefore you've copied scrambled content. When you burn it to recordable media it turns unplayable [you're likely to hear audio though], because you didn't copy the descrambling keys, nor marked protected sectors as scrambled. But before you ask how do you do the latter two, keep in mind that you *can't*. Consumer recordables provide *no* way to copy or setup own descrambling keys and therefore the only way is to descramble content prior recording. How is another question [which I don't feel capable to answer].

It seems clear that in terms of data and filesystems,

I'd challenge the "terms of data" part. The fact that you can mount it is not mystery, because not everything is scrambled. Most notably sectors describing/defining file system layout are not, which is why it's never a problem to mount protected media and list files on it. Not even whole video content is scrambled, most notably menus are commonly not, so you can always "navigate"... A.

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