rtmpdump 0 bytes no causing by proxy failing.
rtmpdump 0 bytes yes causing by youtube-dl making rtmpdump using limelight.
questioning reason limelight failing even when yes good proxy ??? no know.
make rtmpdump yes using akamai, no using limelight.
this result, if no working for you computer.
maybe limelight working with better rtmpdump command?