This technical report discusses three metrics of user engagement with online media. They are Commenting frequency, Voting frequency, and Voting balance. These relative figures can be derived from established, basic statistics available for many services, prominently YouTube. The paper includes case a study of popular YouTube videos to illustrate the characteristics and usefulness of the measures. The study documents the range of observed values and their relationships. The empirical sample shows the three measures to be only moderately correlated with the original statistics despite the common numerators and denominators. The paper concludes by discussing future applications and the needs of the quantification of user interaction with new media services.