Green Screen In Sony Vegas
(Im using Green screen as a general term, you can screen any solid color,and for this tutorial we will be using White) First of all, Film the player against this background...
Location
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source video
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Now open Sony Vegas
Right click video track 1,and click Insert video track. So you now have 2 video tracks. Place your clips on the timeline - Make sure your Player clip is on top and your Background is on the bottom.

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Goto video FX(1) and select chroma keyer, Drag the blue screen effect onto Video track 2 (2) .
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Click the color picker(1) and select the color you want to remove from the timeline(2). in this video I select White.
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Adjust the settings as needed to remove the color.
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I have now removed the color but now I have a big mess(hud,bottom split screen) Lets clean it up now. right click the video track 2 clip and select Pan/Crop

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Adjust the X and Y settings(1) to move the player around(2).
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Now click the mask option(1) select the anchor creation tool(2) Now click an to make an outline around the player(3)

Final Outcome