Great guide! Really nice job!
Another way to record an in game sound is to enable a windows "stereo mix", use any recording application of your choice (windows recorder, audacity, etc.) and select stereo mix as your input.
Also a question: is there efficent way to record a sequence in slow motion using a re_export command? A start button always setup re_speed at 1.0... If I wanted to record a video in 50% speed I was exporting frames at 120 FPS and later on changing framerate in VirtualDub to 60 FPS when making an .avi, but I don't think this is efficent, and most likely there is a better way.