You just need to use this method. The important part is setting your referrer (Referring Page) to http://trial.autodesk.com/

http://trial.autodesk.com/SWDLDDLM/2013/BDSPRM/ESD/Autodesk_Building_Design_Suite_Premium_2013_Englis h_Win_32-64bit.part01.exe
http://trial.autodesk.com/SWDLDDLM/2013/BDSPRM/ESD/Autodesk_Building_Design_Suite_Premium_2013_Englis h_Win_32-64bit.part02.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSPRM/ESD/Autodesk_Building_Design_Suite_Premium_2013_Englis h_Win_32-64bit.part03.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSPRM/ESD/Autodesk_Building_Design_Suite_Premium_2013_Englis h_Win_32-64bit.part04.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSPRM/ESD/Autodesk_Building_Design_Suite_Premium_2013_Englis h_Win_32-64bit.part05.rar

This is about 21 gig in total...



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