That was a great preview. It kept making me really want to play the game, until I remembered I'd already played it
Good stuff.
The character switching works very similarly to DOTT's, nearly identically in fact. If you're playing as Fone, icons of Phoney and Smiley are always on screen and you can click them to switch around between characters at will through large parts of the game. Unlike DOTT the three characters can't "flush" inventory items to each other - their paths don't actually cross all that often (if ever, aside from Phoney and Smiley being able to talk to each other through the door of the tavern) - but actions you take as one character will often help another character along.