I had a requirement to configure a bunch of user accounts identically with regards to group membership. I wrote a small powershell script so that a single account could be configured and then all group memberships copied from that group account.
Below is the script I used:
$sourceUser = ""
$destUser = ""
Get-ADUser -Identity $sourceUser -Properties memberof | Select-Object -ExpandProperty memberof | Add-ADGroupMember -Members $destUser -PassThru | Select-Object -Property SamAccountName