HD is supported, but we haven't enabled it yet for vLine link. We're waiting until we can do a better job detecting whether both ends can handle the HD stream, since the current WebRTC code doesn't do a great job of CPU load feedback (e.g., sending a 720p HD stream to a low-powered machine).

If you want to try out HD, register for a developer account at https://vline.com/developer/ and try the "Web Client". There is a drop-down menu on the "Video Call" button that lets you select HD (make sure to also choose that when you answer. The other option is to try GitTogether, which is just our Web Client with a GitHub login: https://gittogether.com.