I'm not sure what the difference between a mask and a matte is but what I want to achieve is the following. I want to create my own shape which I will use as a window through a video scene to see another scene beyond. I did this to a certain extent with making a black shape created in photoshop with a transparent background but I couldn't work out how to get the black of the shape to get replaced by the 2nd video track. As well as this I would like to achieve 2 colored & feathered edgings/rims around the 'window'. Thanks for any help you can give.
If you use a Photoshop document with transparency, the transparent areas will be "filled" , no the solid one. To use it as a mask in FC you need to use the "Alpha Travel Matte" function.
You can just make a black and whithe document in Photoshop. The white areas will be solid in Fc, whilethe gray level will determine the transparency in FC, being the black 100% transparent.
In this case you need to set the foreground layer as "Travel Matte Luma".
More in the Biscardi's tutorial about mattes and masks here in the forum.