The ballot and the instructions to fill it out are in the original article:
Instructions for VA military members in Section 7
Okay, the ballot as constructed does not require the address of the witness and provides no place for it. It does require the address of the notary if notarized, which would be written wherever the seal is applied. The commonly accepted practice for notaries.
The instructions for VA do not specify the need for address of the witness.
The link you provided (http://www.fvap.gov/.../va/index.html) recites:
Block 7: Sign and date in the presence of one witness. The witness must sign and date the form.
but the link at http://www.fvap.gov/resources/media/vagVA.pdf recites:
No notary or witness required except when a voter is unable to sign the application due to a physical disability or inability to read or write.
F. Federal Write-In Absentee BallotAdditionally, for registered Virginia voters, the FWAB can serve simultaneously as an absentee ballot request and ballot for Federal offices as long as it is received 5 days before the election. The FWAB Declaration/Affirmation must contain the residence address where the voter is registered in Virginia, the voter's current military or overseas address, and the voter's and witness' signature and date. The witness must provide his or her printed name and address in Block 6.
II. Uniformed Services ...
C. Notary/Witness Requirements
FPCA: No notary or witness required except when a voter is unable to sign the application due to a physical disability or inability to read or write.Returning a Ballot: The oath on the envelope must be witnessed and the address of the witness included.
NOPE NO WITNESS ADDRESS AASKED FOR!