A method of placing an ad in a video in an original format may include producing a transcoded video in a proxy format which is a representation of frames of the video in the original format. The transcoded video in the proxy format is convertible to other formats for output. The method may include selecting the ad from a set of ads, selecting a location within a frame of the transcoded video where the ad is to be placed, selecting frames of the transcoded video where the ad is to be placed, placing a placeholder in the transcoded video in the selected frames at the selected location, and storing the transcoded video in the proxy format. When the transcoded video is presented to a user on a display device, the selected ad is inserted in place of the placeholder.