In a general aspect, a system for media playback can include a first media playback device configured to receive a media stream from a media casting device over a data network, the first media playback device being a member of the media playback group and a second media playback device configured to receive the media stream, the second media playback device being a member of the media playback group. The first media playback device and the second media playback device can be collectively configured to designate one of the first media playback device and the second media playback device as a leader playback device of the media playback group. The playback device not designated as the leader playback device can be designated as a follower playback device of the media playback group. The first media playback device and the second media playback device can be further collectively configured to determine a clock offset between the leader playback device and the follower playback device. The leader playback device can be configured to receive a broadcast of the media stream over the data network; play the media stream; and provide the media stream to the follower playback device. The follower playback device can be configured to play the media stream in synchronization with the leader playback device based on the clock offset.