The two buttons were
The download now, was a direct link to the gift. In other words you would want people to use the get gift button, and join your list, but they could get the gift without signing up.
I have just checked the stats of the whole of the giveaway.
For those who had over 100 people downloading the results of direct download (no sign up) was less than 1%
Those who have less than 100 people the rate was higher, because they were getting the same sort of numbers of people who were downloading everything.
The moral is give an IMer the choice of sign up or not, and it seems that most will sign up. There is no need to force people, they will do it automatically.