To the best of my knowledge, WHICH IS PROBABLY WRONG, the
POSITION output from the VS is needed by the PS even though it is not accessable to YOU.
Thats why you need to send another copy of it via a 'spare' TEXTCOORD.

And I THINK the reason you can see anything, is cause you are translating the
model using the "matWorld" matrix. It doesnt account for camera position I believe.
So you should be translating "Out_Pos" with "matWorldViewProj" to see the model,
even if you continue using "matWorld" with "OutCoords".