Vegas is probably your easiest and most effective method since you have access to it. For the event (video) you want to work with, click the "video Event FX", then select "Chroma Keyer." Use the eye dropper to select the color you want to replace, slide the threshold knobs back and forth to get just the color you want, add alittle blur if needed. Mark the "show mask only" to see better what you are working with.