A video advertising system, methods, and apparatus are disclosed, which may include an advertising system, including an advertising server and advertising console, and a user device, which may cooperate to select video advertising campaigns and display video advertisements. In an example embodiment, a method includes playing a video on a display, overlaying markings on the video while the video plays, at a first time while the video plays, measuring a first refresh rate of the video, at a second time while the video plays, performing a first operation on the markings, measuring a second refresh rate of the video at the second time, and determining an estimated area of the video displayed on the display based on the first refresh rate and the second refresh rate. In an example embodiment, a prediction model is trained to output a viewability inference for a video.