Not only that, they'll keep one slot free to SELL access to the last guy to play their library. :D

At least that's what I'll do with my mates if this is true.

Do you guys know how when you buy a DVD/BR, you get a digital copy? Imagine this is true for Xbone games as well. Each game you mark as shared, gets a share copy in the cloud. Anyone in your share group can play this share copy, even if you are playing the actual copy you own. But two share group members cannot access the same share copy at once. This is what both Xbox support and Phil Spencer and others have confirmed today.

What this is saying though, is that while one member accesses the share copy of one game, another share member can access the share copy of another game. And a third can access a 3rd game. And so on. This differs from what we initially thought, which was that while one share member accessed a game on your share library, you could also access any game, but no other share members could access any game in your library.

In the end, who knows. Everything can always change.

In all the reply he never confirm the most important word for me "at the same time".

From what I've gathered so far it seems like the following (right or wrong):

You can share all the games on your account with up to 10 people. These people have access to all games in your library. You can play any of your games at any time, but only one other person will be able to play any game in your library at a given time.

Basically, all your games are there for you to access, However, if anyone else wants to access a given game, they can only do that if none of the other people in your "family" is currently playing it. That means if you have 10 different games in your library, every one in your "family" can be playing a different game at the same time.

The twitter pic is talking about both simultaneously, well the Xbox person is.

To me this is all very clear.

1) For a SINGLE CONSOLE, all users on that console can share the same Live account and thus the same game library.
NOTE: This is identical to having a normal DRM free disc game.

2) For MULTIPLE CONSOLES, a user can select up to 10 other individuals to share the games. Only restriction is a single game can only be played by a single person at a time. So you can play multiplayer with one of those 10 users unless they also had a copy of the game on their own.
NOTE: This is identical to having a normal DRM free disc game.

What MS is doing is simply adding the advantage of a digital system to the physical limitation of a disc. Its no different.

However on option #2 you have some interesting leeway since you can have say 2 of 10 buy a game like COD and then any 2 members of that group can do the mutiplayer too by simply using each other's copies. So you can create a sharing group and maybe rotate responsibilities with games that satisfy's the whole group.

Of course you could always be doing that same thing with a local group so its not like there is much difference beyond having to had eachother the game.

No they have not. No one from MS has said that and even this OP specifically says "different".

even more confusing. I doubt M$ would work this way, but how knows?

Seperately Microsoft have confirmed that for any one physical disk, the disk's owner will be able to play the game, and one of their ten family members will be able to play the digital share copy at the same time.

So if you have a sharing situation set up with say one friend, you have literally just halved the cost of your games across the entire generation (assuming you have the same taste in games).

In a pool of ten, five people could purchase the game and then all ten of you could play that game online simultaneously.

This is a huge advantage over Sony's offering (notwithstanding the disadvantages that come with it in terms of required connections).

Can't tell if that Xbox support twitter is a parody account because some of the answers they're giving people are borderline comical.

Like this:

Primary & Secondary Consoles:

Any console you have logged in is a secondary console.  The console you're currently logged into is your primary console.

Anyone who has signed into one of the same primary or secondary consoles has complete access to your games library.  They can play the game at the same time you can play the game.  They have access to your DLC.

Family Group:

Any person you set as a "Family" group member has access to your games library and DLC.  However, if another "Family" group member is playing the game, they will be restricted from playing it.

Scenarios:

You and your best friend regularly play on each other's Xbox One console.  His library is available to you, and your library is available to him.  The caveat is if he's playing a game off your games library or you're playing one off his, the console will have to check in every hour.  When you access someone else's game's library (their secondary console) your console must phone home.

You have a friend you play frequently enough online and you add that person to your Family group.  That person can access any game in your game library that isn't currently being played by anyone else in the Family group.  So if you have 10 Family group members and nine games in your game library, the 10th member of your Family group won't be able to play any of your games.

To continue with the above scenario.  If you have one console in your primary residence, and you are signed in and playing one of your 9 games, 9 of your "Family" group members can also play one of your nine games.

To continue with the above scenario again.  If you have three consoles in your house, one you and three others are playing on, and the other two with 8 other people signed-in and playing the same game, the 9 Family group members can keep playing their game.

What cannot happen is no two Family group members can play the same game from your games library.

Recap: 

Primary console - The console you are currently logged into.  Only phones home once, every 24 hours.

Secondary console - A console that you have previously logged into.  Phones home every hour if it is accessing your games library.

Any person signed into a secondary console or into your primary console at the same time as you, can access your games library.

Family group members - Can access any of your games, however no two family group members can access the same game at the same time.