is there an easy way to read if a DVD was written in UDF, ISO mode, or both? Windows explorer doesn't really show the filesystems, and Nero DVD Speed obviously doesn't as well.
How can I get that information from a disc?
Try Nero Info Tool .Check disc tab.
ImgBurn in read mode also gives this information .
IsoBuster should also show which filesystems are on the disc (even the free version).
ImgBurn in Read mode shows the file system too