I already have the export part done - below is the excerpt from the Powershell script I use to export recordings...
$wpmServer = Server name/ip of the WPM polling engine.
$RecordingId = Recording id of the recording to export. This can be pulled through an easy SWQL query.
$username = User that has permissions to export recordings.
$password = Password of the above user that can export recordings.
$Name = Name of the recording - also pulled from an easy SWQL query.
# Get recording
$recOutput = Invoke-WebRequest -Uri "http://$wpmServer/Orion/SEUM/Admin/RecordingExporter.ashx?action=export&recordingId=$($RecordingId)&AccountID=$username&password=$password" -outFile "$outputDir\\$($Name).recording"