TypeError: Error #1009: when hitting play button on

[mangui]

while hitting play button on http://bem.tv/ using flash debug player the following exception occurs:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at org.mangui.hls.stream::FragmentLoader/_loadfirstfragment()
at org.mangui.hls.stream::FragmentLoader/_checkLoading()
at flash.utils::Timer/_timerDispatch()
at flash.utils::Timer/tick()

after discarding it the playback starts successfully.