First off, you would have to be a multi million dollar bettor for the government to do anything even if they had neteller's records... The government is not coming after every tom dick and harry. The government does not work like that. There are over 2000 online casinos and sportsbooks. The government has gone after WSEX, WTTS, Pinnacle, BOS, Neteller. They have not gone after JOe's book and they are definitely not going after Joe bettor.
Second, neteller has no reason to give the government any type of records. What is the government gonna do? Say, give us your records and then keep on sending money to the gambling sites...
In order for the UK to turn over banking records, the government must show reasonable cause of money laundering to support criminal activity. The UK and the rest of the world does not consider gambling as criminal activity. It is very very unlikely any banking records will be turned over.
What will most likely happen is neteller will volunteerily leave the US market and that is the end of it.
The government (ANd who ever is putting hundreds of millions behind this) are out to stop online gambling, not to waste money.
Sean