Not sure if this worked in earlier versions of DVD Player, but I just burned a miniDVD (UDF-formatted CD/R(W) that contains a VIDEO_TS folder) and it played back perfectly in the Tiger DVD Player.
[robg adds: I haven't tested this one, and I can't do so in 10.3 any more, so I don't know if this is a Tiger-only thing or not...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=2005050714101548