This means that you will give testimony remotely, by telephone. Originals should be sent to the court but if you don't have them, you can send copies with a certification accompanying them indicating that the documents are true and accurate copies. Make sure the court has a number where they can get in touch with you.
"Audio-Visual" technically means both hearing you & seeing you. However, in most instances, giving "electronic" testimony means testifying over the phone. Usually in a child support proceeding, you must designate where you will give the testimony, which in most instances is the SCU in your state, or a notary public or lawyer's office. Additionally, you should strive to send them the originals - I suggest to send them to the Clerk's Office via certified mail, return receipt. In any event, I encourage you to schedule a phone consultation with a NYC Child Support lawyer.
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I agree with the answers already provided. The notice might be confusing but it just means that you will be allowed to give testimony via phone rather than appearing in person. You would be best to send originals but you can send copies so long as you include a statement saying that they are copies of the originals. You should contact counsel in NYC to assist you in this case.
This advice is not meant to create an attorney-client relationship and is a general answer to the question posed.