There's a package on Aminet that will create a DVD dosdriver. I don't recall the name, but a search for "dvd" will bring it up. You can use any CDFS with it, but I think most will fail at the 4Gb limit. It works, but not very well. You can use the DVD as a CD drive without error, but with CacheCDFS I get read errors on DVD disks. AmiCDFS performs slightly better.
AllegroCDFS is the only filesystem that currently supports DVD UDF directly. You should have no problems with that, either with the default driver, or one created by that package above.
If you want to play DVD video, you're out of luck unless you have a top-of-the-line PPC card. Or a decoder card... maybe through the Mediator?
