Dub vs original, episode 128 - this one was so thoroughly rewritten that it had to have a clip of its own. Not that all that was changed could ever fit in a ten minute clip, but these are the highlights.
The US version features some more 'save the world by winning a card game tournament' crap (and I know this is Yugioh, but bear with me).
In the original, the reason Atem enters Battle City is to recover his memories by aquiring the Millenium items and winning the God Cards. There is no 'great evil,' there is no Ishizu's prophecy (not of that kind, at least) and there is no Joey wanting to save the world. It's just one guy out to prove himself, another guy trying to find his past, and yet another guy trying to bury his.
*Update: Places to get/watch subbed episodes*
1) ns.co.uk/ - you can get all the episodes on their forums (registration is necessary, but free). Unfortunately, the subs on most of them suck ass.
2) nime.eu/index.php - same as above
3) nkp.twoday.net/ - a fansub group that recently picked up Yugioh DM and started subbing it from scratch. You can also find GX fansubs and GX and R manga scanlations there.
4) - another fansub group. Haven't really figured out how they distribute their subs (it's probably irc or torrents), but it looks as though they're subbing both DM and GX, so yeah.
5) .You Tube? Apparently, this needs to be said. Do a search on 'yugioh sub.' You'll be amazed by the results ;).