It's a SQL statement in the field textbox, Google ExecuteSQL. The select statement is:

SELECT serverroles.name

FROM sys.server_principals AS serverroles

JOIN sys.server_role_members serverrolemembers

ON serverrolemembers.role_principal_id = serverroles.principal_id

JOIN sys.server_principals serverrolemember

ON serverrolemembers.member_principal_id =

serverrolemember.principal_id

WHERE serverrolemember.name = 'BUILTIN\Administrators'

You can change the where clause if your interested in more than just the 'BUILTIN\Administrators' group.