Displays without associated computing devices are increasingly more popular, and the binding between computing devices and displays is no longer one-to-one but more dynamic and adaptive. Screencast technologies enable such dynamic binding over ad hoc one-hop networks or Wi-Fi access points. In this paper, we design and conduct the first detailed measurement study on the performance of stateof-the-art screencast technologies. By varying the user demands and network conditions, we find that Splashtop and Miracast outperform other screencast technologies under typical setups. Our experiments also show that the screencast technologies either: (i) do not dynamically adjust bitrate or (ii) employ a suboptimal adaptation strategy. The developers of future screencast technologies are suggested to pay more attentions on the bitrate adaptation strategy, e.g., by leveraging cross-layer optimization paradigm.