I presume he was referring to Mojang's Snapshots and before those, the prereleases. And of course Minecraft was "released" in an Alpha stage. I'm not agreeing with him though - even Mojang didn't release an alpha version of their launcher, it's just asking for trouble.
Yeah, the snapshots are betas of the next version. There were alphas before that, which probably only the people at Mojang were testing.