This appears to be a genuine update. Read the file description:
Certain highly-detailed scenery add-ons that make use of large satellite images may not display correctly in Flight Simulator X. Specifically, you’ll notice large rectangular areas that are black or dark blue, where the proper ground texture does not draw at all. Microsoft has confirmed this issue to be a bug in the Flight Simulator X terrain display engine. To resolve this issue, download and install the Flight Simulator X update for your language, linked below.
yes, i went to fsinsider throught he link in my start menu for FSX and it apears to be oficial so i downlaoded it and aplied it and the game still runs as great as can be, at least on my comp.
That sounds encouraging, thanks for the feedback.