text: I'd like to use the HTTPStreamingNetLoader package but I can see entries in the package classes
  similar to the following:
  CONFIG::FLASH_10_1
  {
  import flash.net.NetStreamAppendBytesAction;
  }
  I don't know how this works but presumably its saying that this package won't work/compile
  unless flex is using 10.1 as its 'target version'.
  For my current project I cannot force the users to 10.1.
  Is it worth my time looking at this class at all ?
  PS I need to enable seeking if part of the video has already been downloaded
  and the user loads the video again - OSMF always seems to return the canSeek as
  false for progressive downloads ....
  regards
  To use 10.1-only features like HTTP streaming, you need to set the compilation flag CONFIG::FLASH_10_1 (in the project properties) to true. And yes, your users would need Flash 10.1 to use the feature. Currently HTTP streaming is in prerelease, though you can check the latest release notes for info on how to join the prerelease program.