It simply doesn't work, because
it's for Direct3D 9 applications/games, and
Orbiter with built-in graphics is Direct3D 7.
It would work with D3D9Client for Orbiter_ng, if it was functioning, and because Orbiter uses D3D7, and not D3D9, it won't work with standard Orbiter, unless someone writes a D3D7 wrapper for D3D9 functions that would allow loading D3D9.dll (like for example MGE does it for D3D8 Morrowind game, and thus allows loading ENBseries for it). It won't work with OGLA graphics client either, because OGLA uses OpenGL, and not DirectX.
It isn't rather a HD effect that you were thinking, but [ame=http://en.wikipedia.org/wiki/High_dynamic_range_rendering]HDR lighting[/ame] effect, which was the main function of that D3D9 wrapper from the start, but it can also add
bloom, [ame=http://en.wikipedia.org/wiki/Motion_blur]motion blur[/ame], [ame=http://en.wikipedia.org/wiki/Depth_of_field]DoF[/ame], and [ame=http://en.wikipedia.org/wiki/Screen_Space_Ambient_Occlusion]SSAO[/ame] effects, if application which uses it provides required information to D3D9.dll to use it.
It's a request for a new graphics client development, or for adding Cg shader compiling support to existing
OGLA graphics client, which would add effects known from ENBseries, by applying customized shaders (or building D3D9Client client, that would load ENBseries' D3D9.dll, or adding HLSL shader compiling support to it, so ENBseries wouldn't be needed).