Weird, you'd think of all people one of the developers of this game would know how to pronounce the clan names correctly in that video. I couldn't repress a serious wince every time I heard him say "Uesugi" or "Date". Still, looks pretty awesome, and definitely picking this up just from what I saw.
Well, quite! It's ooo-eh-sue-gi and da-teh. But perhaps they're more interested in bandwagon jumping and don't want to go into to too much depth.