If you have played Warcraft 2, there would be times when you would stmble across some random units - generally a color like yellow or teal - that when you approach them they would join you.
Basically, they are neutral players/units that don't fight or act on their own, and the player who "rescues" them first they will join.
A player can be flaged as Rescueable in the Player Properties. As mylemonblue mentioned, those units will change owner to the first player that gets close to them. You might have seen that there is triggers as well, making units "rescuable"
The term "rescue" probably comes from what kind of campaign scenarios you'll find these units, in Warcraft, maybe even more in Starcraft, and in other games as well. Very often there is a base under siege or some units in a prison or a trapped situation, that rewards you by joining you if you can reach them!
I'm on a page about incorrect corrections, and spent the better part of like two hours trying to get someone to understand that -5^2 = -25, not 25, and then that post had comments get reposted because that group is self sustaining, and that person was in turn trying to explain what I just explained to them. And I'm taking that as a victory
I will be AFK for a couple of days you guys hold down the fort while I am gone. I will be checking in on my phone but that will severly limit me. Be back saturday!
I just got to watch the video because even though I was there I was trying to work out tech problems with the chat since I was the social media guy so I was distracted but check it out guys the video is super fucking great!