By looking at the coordinates of your triangle, the center is approx. at (-0.3, 0.0, -1.0). Therefore the first video makes sense to me.

What I would do, is define the triangle with it's center at (0,0,0). You could do the following:
[pascal]
//top vertex
Vert[0] := 0.0;
Vert[1] := 0.5;
Vert[2] := 0.0;

//right vertex (I think LOL )
Vert[3] := -0.3;
Vert[4] := -0.5;
Vert[5] := 0.0;

//left vertex
Vert[6] := 0.3;
Vert[7] := -0.5;
Vert[8] := 0.0;
[/pascal]

It's common to define objects with their center at (0,0,0). If you want them to appear somewhere else, you just change the model matrix.