You downloaded the video clip from YouTube as not very popular, but widely used FLV format. But how can you easily extract components of this file, if you need just audio or video part of it? FLV Extract can do that without decompressing or recompressing.
NOTE: You cannot change the video/audio format that FLV Extract outputs. It depends on what is contained in the FLV file. If you need a different format, you'll have to use other software to convert it. Or, ffmpeg (command line) can extract from FLV and convert in one step.
NOTE: The AVIs will not play unless you have the right decoders. ffdshow-tryouts can decode FLV1 and VP6F; make sure they're enabled in its configuration dialog.
NOTE: H.264 elementary streams are not widely supported by players, but you can use DGAVCDec to load them with AviSynth for editing.