This free site from the University of Oxford features public lectures, teaching material, interviews with leading academics, information about applying to the University, and much more. All the material is arranged within a series of related talks or lectures and may be in audio, video or document format.
Content is being added regularly to the site. All content is free for you to download and watch or listen to.
Below are some examples of podcasts which all have the keyword tag 'united nations'. There is a search facility on the website.