The following shows how to query the 7digital api from powershell.
[xml]$data = (invoke-webrequest -uri http://api.7digital.com/1.2/release/details?releaseid=951886`&country=gb`&oauth_consumer_key=$my7digitalKey | select -ExpandProperty Content)
This provides an in memory object that you can walk the tree.
This is how I investiagate most xml/json feeds.
I am not publishing my key so get your own and set it in your profile: