the app does not support app audio and video codecs. If you have adobe AC3 audio codecs in the video files (this is one example of an unsupported codec) audio will not play.
for buffing issues you are seeing. the wireless stick has a max wireless stream speed of 6Mb/s to a single stream. If you have multiple streams this 6Mb would be divided among all streams. If the videos are very high quality you any be exceeding the streaming capabilities of the device and causing it to buffer.
as a work around you can convert the video files to common codecs like MP4 video codec and MP3 or AAC sudio codec and reduce the quality of the video so it does not exceed 6Mb/s bitrate. if you plan on doing multiple simultaneous streams it would need to be in a lower bit rate. For example if you want to do 3 streams at the same time the video should not exceed 2Mb/s bitrate.
