It was the _CommonRedist folder that holds the DirectX shit. From what I heard, They (at least attempted to) lumped all installations of DirectX and whatnot together, so you didn't have to reinstall it over and over again every time you install a game. It frees up some hard drive space at least. There was one round, where each game had literally 0 bytes to install, and then some people have had a second round where it ranges from 50-200 MB per game, apparently to reinstall some lost files.
Again, this is just what I heard, but it seems weird that Valve wouldn't say anything about it.
If you laid out all of your blood vessels, end to end, you would die.
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