The plug-in's are included in Nero 6, however, separate serial numbers are required for activation. To see what is activated, click on the flaming Nero logo (top left) then click the Serial Numbers Tab. Even though I had "Nero 6 Ultra Edition" activated, I still required a "Power Pack" activated to get rid of "available plug-in" messages.
I have found that if I compress to a custom size which allows 10Mb per minute of video I can get good quality video and 2-ch sound BUT ONLY if I use the Fast Encoding (1-pass) option, NO sound available with High Quality (2-pass) option???
I hope this helps!