President Obama's weekly messages were recorded as videos, and uploaded each week to YouTube, on an official White House channel. They were also posted on the White House web site. While they were still broadcast on the radio in some areas, the focus shifted away from radio as a means of communication, and toward the internet and social media.
Each address has an official title, which is in quotations. Alternate titles, in brackets, are taken from The Obama White House channel on YouTube, or other official releases. For the first few months, there were no alternate titles available, so I just listed the topic.