I think he is suggesting VCs want much larger exits than the average founder (at higher risk). Isn't most of Y combinator's success from just a couple massive paydays (airbnb and dropbox etc)? Whereas an exit like reddit in the 15 - 20 MM range is considered a big win for the founders, but quite "meh" for the investors. VCs need big wins to be really successful.
I'm not a VC, but if $5MM (7-digits) is raised and the exit is only $20MM (8-digits), that's an okay return, but it's probably not what the people who put money in were hoping for. 4x seems good until you consider the tremendous risk the investors exposed themselves to.