À savoir si on peut toujours passer un compte qui a téléchargé la beta pour qu'un autre la télécharge à partir de ce compte et joue avec un autre.

J'ai rien compris?.Mais c'est point grave. ;)

Apparently, Microsoft has temporarily locked out 23,000 thousands LIVE users who took advantage of a now resolved exploit in Call of Duty 4 beta. The exploit allowed participants to sign in on a different machine, use their beta token and download the beta again. Game site Xbox-Scene has a memo from an "internal Microsoft source" who details what's gone down:

There was an exploit (it's been resolved), in the Call of Duty 4 beta. The public beta had 100k valid participants who qualified and were provided special tokens which allowed them to download the COD4 beta from Marketplace. There was an exploit that enabled valid beta participants to sign in with their accounts on a different machine, use their beta token and download the beta. The beta was then fully functional for any LIVE profile on that 2 nd machine (even after the beta participant's account was removed). Approximately 23k consoles were used to take advantage of this exploit to illegitimately access the COD4 beta.
The exploit has been fixed to prevent any additional users from illegitimately accessing the COD4 beta.

The current POR is to issue a 24-hour console lockout that will prevent these 23k users from using their consoles to sign in to LIVE. These users will also receive a message in the dash with an explanation as to why their console has been locked out for 24 hours for violating the LIVE TOU and a warning that more severe actions may be taken if they attempt a similar action in the future (console could be banned permanently, etc.). Again, this is not a permanent console ban - It's more of a "slap on the wrist" and a warning to these 23k users who used this exploit