"you must indicate your intent to buy within the Intend to Buy date range listed for each game to be eligible for the extra Coins". The Intend to Buy date range is 4 weeks after release.
It doesn't say register the game, it says indicate your intent to buy. Are you sure you intended to buy it before it released?
Someone on another forum is where I first heard about this so I don't know what to believe. They got 80 coins like this:
50 for registration
10 for intend to buy
10 for registering within 4 weeks
10 for post play
I guess I'll just have to test it out for myself to see.
EDIT: Here, this is from the FAQ:
How many Coins will I earn for taking the different surveys?
Registration Survey*
Wii Games = 50 Coins
DS Games = 30 Coins
DSiWare = Not Eligible
Wii Shop Channel game and Wii Channels = Not Eligible
Nintendo DSi System = 160 Coins (Registration, Survey, and Club Nintendo Link Required)
Wii and Nintendo DS Lite Systems = Not Eligible
* Earn 10 bonus Coins by registering the game and taking the survey within 4 weeks of the game's release.
Post Play Survey
Wii Games = 10 Coins
DS Games = 10 Coins
DSiWare = 10 Coins
Wii Shop Channel game and Wii Channels = 10 Coins
Nintendo DSi System = Not Eligible
Wii and Nintendo DS Lite Systems = Not Eligible
Intend to Buy Survey (Click here for more information on Intend to Buy.)
Wii Games = 10 Coins
DS Games = 10 Coins
DSiWare = Not Eligible
Wii Shop Channel game and Wii Channels = Not Eligible
Nintendo DSi System = Not Eligible
Wii and Nintendo DS Lite Systems = Not Eligible
Note two things: It mentions getting ten coins for registering within four weeks after launch under the regular registration. The Intend to Buy section does not mention any time frame.