Get all high quiality azure friday episodes for Build trip

AzureFriday

$(Invoke-RestMethod -Uri http://channel9.msdn.com/Shows/Windows-Azure-Friday/feed/mp4high)|%{$pattern = "[{0}]" -f ([Regex]::Escape( [System.IO.Path]::GetInvalidFileNameChars() -join '' )); @{ FileName = [RegEx]::Replace($_.title + ".mp4", $pattern, ''); Url=@($_.group.content.url |sls high.mp4)[0].ToString()} }|%{if(!(Test-Path -Path $_.FileName )){Invoke-WebRequest -Uri $_.Url -OutFile $_.FileName}}

Added check for if file name exists and clean file name of invalid characters.