Looking at the Obama campaign's videos from April 2012, of which 32 were found, one sees some focused on highlighting or encouraging and inspiring grassroots activity, others with more of a focus on policy, issues, positions and accomplishments, and still others targeting Romney or rebutting Romney attacks.  Note that these categories are artificial and are not mutually exclusive.  For example, quite a few of the policy-oriented videos include jabs at Romney.  Other examples of videos serving multiple objectives are the Earth Day video, which includes a major dose of accomplishments but ultimately aims to bring people on board Environmentalists for Obama, and "One Chance" which highlights an accomplishment, the killing of bin Laden, and at the same time questions Romney's decision making.