Because of Ubisoft's persistent insistence on "blending single- and multiplayer experiences," this Watch Dogs video doesn't so much show you a multiplayer mode, but rather what you can expect from others as you play the game. As there are always other people in Watch Dogs, and other people are always jerks, you can expect that other people will be jerks in Watch Dogs and try to hack you.
In all honestly, this facet of the game looks kind of neat in moderation. A little cat and mouse game, somewhat reminiscent of Assassin's Creed's multiplayer, but with some modern tech touches like taking control of surveillance cameras. Now, if other players are constantly hacking you, this will probably get old quickly.
And, really dude? You hid in a taco truck? When I see one of those, it's literally the first place I'm going.
Watch Dogs will be out on May 27, 2014 for the PlayStation 4, PlayStation 3, Xbox One, Xbox 360, Wii U, and PC.