There is no official gameplay yet, just the trailers. I would not trust "leaked" gameplay videos because they're usually bait so the uploader can get thousands of views. I'm not sure when gameplay will come but expect to see more from Rockstar as GTA V's release gets closer and closer.
"I could easily entice you to kill everything that you love."
Rockstar hasn't done E3 since 2001 and they've never released game play footage (with the HUD and so on) of any GTA game. At best we might get a screen shot or two with the HUD up near release but probably not.
Band/Artist I've been listening to way too much: Fallon Bowman/Amphibious Assault. https://soundcloud.com/fallonbowman