shader problem

I need to remove the green screen behind the character ...

I tried this code

 Shader "Chromakey/Mask" {
 
 
     Properties {
 
         _MainTex ("Base (RGB)", 2D) = "white" {}
         //_MaskCol ("Mask Color", Color)  = (1.0, 0.0, 0.0, 1.0)
         Transparency ("Transparency", Range (0,1.0)) = 0.5
     }
 
     SubShader {
         Tags {"Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
         LOD 100
         
         ZWrite Off
         Blend SrcAlpha OneMinusSrcAlpha 
 
         CGINCLUDE
 
             #include "UnityCG.cginc"
             
             uniform float Transparency;
             
             half3 NormalizeColor (half3 color) {
                 //return color / max(dot(color, half3(1.0f/3.0f)), 0.0001);
                 return color / dot(color, fixed3(0.5,0.5,0.01));
             }
 
             half4 MaskColor (half3 mCol, half3 cCol) {
                 //half4 d = distance(NormalizeColor(mCol.rgb), NormalizeColor(cCol.rgb));    
                 //return ((mCol.g - (mCol.r + mCol.b)) > Transparency ) ? d : half4(mCol.rgb,1.0);
                 return ((mCol.g - (mCol.r + mCol.b)) > Transparency ) ? half4(mCol.rgb,0.0) : half4(mCol.rgb,1.0);
             
                 //float e = 0.04f;
                 //return ( mCol.g <= e && mCol.r <= e && mCol.b <= e) ? half4(mCol.rgb,0.0) : half4(mCol.rgb,1.0);
             
             
             //float f = 1.0f;
             //if ((mCol.g - (mCol.r + mCol.b)) > Transparency )
             //    f = 0.0;
             //return half4(mCol.rgb,f);
     
                 //return ((mCol.g - (mCol.r + mCol.b)) < Transparency ) ? half4(mCol.rgb,0.0) : half4(mCol.rgb,1.0);
             }
         ENDCG
 
         Pass {
             Lighting Off
             //Cull Off ZWrite On Lighting Off Fog { Mode off } 
             //Blend SrcAlpha OneMinusSrcAlpha
             CGPROGRAM
                 #pragma vertex vert_img
                 #pragma fragment frag
                 #pragma fragmentoption ARB_precision_hint_fastest
 
                 uniform sampler2D _MainTex;
                 uniform float4 _MaskCol;
 
                 half4 frag (v2f_img i) : COLOR {
 
                     half4 col = tex2D(_MainTex, i.uv);
                     half4 mask = MaskColor(col.rgb, _MaskCol.rgb);
                     //return col * mask;
                     return mask;
                 }
             ENDCG
         }
         
         
         
     }
 
     Fallback off
 }
 
 

but the problem , some green line around the character didn't disapper , is there away to change it to clear all the green layer ?

then I searched a lot and found this site talk about the same situation , but by using mask at the same image ( normal image and mask at the same image )

but the shader dosen't work fine

http://www.unity3d-france.com/unity/phpBB3/viewtopic.php?f=8&t=901&sid=bd96eaad6e6c1b2d40e34679a2bc73cf☆t=10

 Shader "Custom/VideoAlpha" {
    Properties {
       _MainTex ("Base (RGB)", 2D) = "white" {}
       _AlphaOffsetX ("alpha offset x", float) = 0.5
       _AlphaOffsetY ("alpha offset y", float) = 0
       _Cutoff ("Cutoff", Range (0,1)) = .5
    }
    SubShader {
    AlphaTest Less [_Cutoff]
          CGPROGRAM
          #pragma surface surf Lambert
    
          sampler2D _MainTex;
          float _AlphaOffsetX;
          float _AlphaOffsetY;
    
          struct Input {
             float2 uv_MainTex;
          };
    
          void surf (Input IN, inout SurfaceOutput o) 
          {
             half4 c = tex2D (_MainTex, IN.uv_MainTex);
             IN.uv_MainTex.x += _AlphaOffsetX;
             IN.uv_MainTex.y += _AlphaOffsetY;
             half4 d = tex2D (_MainTex, IN.uv_MainTex);
             o.Albedo = c.rgb;
             o.Alpha = (d.r*-1)+1;
          }
         
          ENDCG
       
    }
    FallBack "Diffuse"
 }

i added to the material then add this image

but no change at all , where the problem ?

thank you ...

Note : I need it to work with Images and video