By default most players do not cache the input from stdin, here is a few options you can pass to some common players:
Use the --player option in Livestreamer to pass these options to the player.
VLC version 2.0.1 and 2.0.2 contains a bug that prevents it from reading data from standard input. This has been fixed in version 2.0.3.
Some versions of 64-bit VLC seem to be unable to read the stream created by rtmpdump. Using the 32-bit version of VLC is a workaround until this bug is fixed.
Upgrading to version 1.7 or newer will solve this issue since reading data from standard input is not supported in version 1.6.x of MPC-HC.
Twitch sometimes returns badly muxed streams which may confuse players. The following workaround was contributed by MPC-HC developer kasper93:
To fix this problem go to options -> internal filters -> open splitter settings and increase “Stream Analysis Duration” this will let ffmpeg to properly detect all streams.
Using --player-passthrough hls has also been reported to work.