FWIW, It is described in the FAQ:
What is the Release?
When US members request to withdraw the funds they will be asked to agree to a Release which, in broad terms, is an agreement between NETELLER and the member that each releases the other from potential legal claims. US members do not need to agree to the Release in order to request and receive the payment of funds. However, US members who do not agree to the Release will, in turn, not be released by NETELLER.
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