read cd's but not dvd's?

[Josh Carroll]

> That would probably be because DVDs use the UDF format.  ISO9660 is only
> for CDs.

Actually, you can mount some DVDs with mount_iso9660, but obviously it
won't work properly for large files.

Note that I don't think you can just mount a commercial DVD with
mount_udf and start copying .VOB files off if it. You'll need to use
something like libdvdread, etc. I had the same problems with my DVD
drive, and thought it was my hardware or a kernel bug, but it's simply
not possible to read files off an encrypted DVD after mounting with
mount_udf.

Josh