This study mainly investigates the motivations of YouTube and Flicker users for posting videos or images/photos on each service. The motivational framework with ten factors such as enjoyment, self-efficacy, learning, personal gain, altruism, empathy, social engagement, community interest, reputation and reciprocity were used to test the motivations. Those who are users of YouTube and Flickr were recruited from Amazon Mechanical Turk to participate in online surveys. Findings show that learning and social engagement are the two most highly rated motivations. Altruism was rated relatively low, although it was strongly correlated with all other motivations. Personal gain was rated as the lowest by both users but Flickr users rated personal gain higher than YouTube users. Findings from this study could be applicable to specify user motivations for using the services and to upgrade the designs of the services in the future.