First four out are the prognosticators prediction of the last four teams that don't make the tournament, numbers 69 through 72 if you will. Last four in are the last four to make the tournament, in other words 65 through 68.
And to further clutter the end of the bracket, they now talk about "First 4 Byes". Those are still bubble teams, but those that would be just ahead of the 8 play-in teams. Essentially, teams 57-60. You have to remember though, these last ones in may not be 15-16 seeds. Sometimes the play in game can occur as far up as the 11 seed position.