I am implementing a media player that plays a stream from a remote machine. Via my app I can control the remote machine (e.g. seek to second). Works like charm, but: The Android
The problem might be not only at Android Media Player. Server that is streaming video should support need format.
If it's mp4's you need to install h264-pseudo-streaming module (same for HLS) If it's MSS (microsoft smooth streaming) - there are special modules for IIS.
Also, after user 'makes seek' that means Native Player will send range request, that should be supported by server. Nginx supports them by default, ISS & Apache have some issues with this. Though easy configurable.