The Motion Picture Association of America (MPAA) also brought a civil case against Dotcom.
Mr Mansfield believed it was "highly likely" Judge O'Grady would also order the MPAA case to be delayed.
"It's consistent with what we do here. If there are allegations of a criminal nature being made, then the civil allegations wait, and are heard behind that."
Dotcom, Mathias Ortmann, Bram van der Kolk and Finn Batato were indicted on 13 charges including copyright infringement, racketeering, money laundering and fraud.
The FBI laid charges in January 2012.
In an earlier case, Van der Kolk's legal counsel Grant Illingworth QC said the United States allowed confiscated funds to pay for New Zealand legal resources, but the Megaupload group could not spend it on expert witnesses outside the country.