Container implies that it holds something. I was hoping that each container would hold one type of website that i often have many open - such as youtube. I want a youtube container that I could throw videos in to watch later. Watched several how to videos for this adon but nothing was said about that. Tried to see if it would work like that. Don't think so.
Better if Firefox called this thing "accounts" or something like that as all I can figure out is that it separates accounts.
Somebody tell me I'm wrong and it works that way the name implies.