First, let me say that OS 9.0.4 with DVD Player 2.2 on my G4/350 works great! No popping, no sync issues, etc.
On to the topic...
Using 9.0 and DVD player 2.0, I was limited to watching DVDs on the monitor connected to my AGP card ONLY. If I tried to move my DVD window off screen, it would stop at the screen edge.
Now, with DVD Player 2.2, it allows me to move the DVD player window to my Xclaim VR 128 card. The movie plays just as good on that card as it does on the Rage 128 Pro AGP card.
Why does it matter? The Xclaim VR 128 has S-video and Composite Video out. I can now connected my computer to my television and watch DVD movies on my TV from my computer. Yes, soon I will just get a stand-alone DVD player, but until then, I'll just use my computer.