When he said full flash he meant an hot shoe mount flash. Typically people refer those as full flashes over the built in one...just fyi. I liked the last one, only if that one guys head was out of the shot.
Well, he did say "fill flash" and not "full flash" ... fill flash fills in the shadows, mostly so those you'd get taking photos against a bright background or against the sun.
In the case of these photos, though, I'd say: any use of flash would have ruined capturing the atmosphere. While 3 slipped towards the "blooper" side of things, as she probably moved while laughing, and you didn't really hold the long shutter speed, or didn't get the focus all right in the dark, they mostly have "atmosphere", and I like that aspect about them. 1 is perfect, I say, any use of any kind of flash would seriously have changed the light situation, which I guess you did not WANT changed. 2 is just a bar snapshot, the usual kind, pulling faces and all that... and 4 is another one that nicely works with the ambient light and captures the atmosphere.