Get-ADGroupMember -Identity 'Remote Users' | Select Name, SamAccountName | % {
    $n = $_.Name
    $g = Get-ADPrincipalGroupMembership -Identity $_.SamAccountName | Select Name
    [pscustomObject]@{
        Username = $n
        GroupName = ($g.Name -join ',')
    }
} | Export-CSV '{Path}'