This is OtherSide, a wep app that allows you to share and see other people's YouTube subscriptions.

When you click the "Begin" button, you will be taken to YouTube's Oauth page to grant OtherSide permission to view your YouTube subscriptions if you have not already granted permissions.

OtherSide will then create a unique link for you to give people so they can see what you see on Youtube. The link will expire in a week's time.