# Needs the path where your dll is
Add-Type -Path "C:\taglib-sharp.dll"

Function Get-VideoDetails {
    param ($targetDirectory)

    Get-ChildItem $targetDirectory -Include *.mp4 -Recurse -Force | ForEach {
        $video = [TagLib.File]::Create($_.FullName)

        New-Object PSObject -Property @{
            Name = $_.FullName
            Duration = $video.Properties.Duration.TotalMinutes
		}
    }
}

# Supply your video directory
Get-VideoDetails "C:\Users\Wesam\Documents\MEGA\EggHead\Courses" | Sort Duration -Descending | Group-Object Item | %{
    New-Object psobject -Property @{
        Item = $_.Name
        Sum = ($_.Group | Measure-Object Duration -Sum).Sum
    }
}