This is referring to Ventrilo. I use "vent" as a generic term for group chat, even though I never really used Ventrilo as far as I remember. "Vent" is the plural conjugation of "Skype"
@mcc I was a Ventrilo kid back in the day, but I haven't thought about it in so long that I assumed "in vent" was similar to "in jest", as in "I said this as part of a venting session"