This is something I stumbled upon weeks ago while playing through the Xbox version of Shenmue II with my buddy.
We had a really good laugh and forgott to actually capture it somehow. I also though I'd be able to replicate it.
Since I'm so busy with talking to Fangmei right now, I finally tried it and succeded. That means this glitch isn't random and can be done by anybody. I haven't tried it on the Dreamcast yet. Maybe someone can quickly do this?
Use the "map glitch" to pass the loading barrier in the White Dynasty Qr. and walk into the preloaded part of the Lucky Charm Qr. Fangmei will walk through there on her way from Man Mo Bistro to Complete Clothier round about 1:20 p.m. around the time you'll have to do the chawan sign. Don't forget to talk to Eileen so she and Fangmei hang out at the bistro for sure.
I guess the game has problems loading Fangmei's animations because you're talking to her while technically still being in the White Dynasty Qr, an area that she isn't supposed to be in. Those weird jumps are the dummy motion wich the game will load to prevent total crashes.