BTW, just another update about the performance of these disks. I mentioned that I had trouble playing the first disk without the picture breaking up. Well that turned out to be a little misleading, something that made me think that these disks were worse than they actually are.
What happened is that I was using the DVD to backup some mpeg files (originally made for VCD's and SVCD's) directly to DVD. It turns out that while my DVD player will play mpeg1 and mpeg2 (directly from files on the DVD) that it is very temperamental when doing so, particularly on the SVCD mpeg2 files. So when I burn a regular movie on these DVD's they seem to playback fine. As do the VCD mpeg1 files but the SVCD mpeg2 files break up. It's just something with this player and I've previously noticed it happen with other media too (though I had temporarily forgotten about it as it's not something I do very often).
Not that it's really important but just in case anyone is wondering. I have a bunch of old movies in VCD and SVCD (mpeg1 and mpeg2) format on my hard-drive, I made these ages ago before I had a dvd-burner. I've found that instead of burning VCD's or SVCD's with them that I can just copy them to folders on a data DVD and my player still plays them, so I can put 3 or 4 of these movies on one DVD like that. While these files will play directly as a raw mpeg I've found it works better if I use nero to create a VCD (or SVCD) to a virtual drive or iso image and then extract the actual video files (aviseq01.mp2 etc) from the image and burn them to the data DVD. The VCD files actually play ok either way but the SVCD files tend to break up and misbehave unless I do the trick of making the SVCD and then extracting the aviseq files.
Anyway I think that (playing raw mpeg2 files) is probably the main reason I was having pixelization and picture break up the other day when testing this stuff. I still dont think these discs are all that great though.