Yes the sounds are from a real world 767.
I used them in this video to get the "realistic" feeling to it...
Yes the sounds are synchronized to the FSX footage...
Nice job there, the sounds really fit to the pictures and enhance the atmosphere. I just saw that you are running the yt channel there. Nice idea and, so far, fun to watch, Vlado.
Seems like you are getting on a big number of planes of all sizes, interesting and useful to catch a first impression from each model then. Keep it up!  :)