I am a total newbie at video editing so please be patient with me. What I would like to do is create a video that that is a composite of a still image "matte" with two different "inner videos". For example, say I record a .mov of person A talking and a another .mov of person B talking somewhere else: I want my final "main" video to be, for a simplified example, a still image of a house (say a .png or some some such) with person A's video playing where one window of the house would be, and person B's video playing where another window of the house would be.
Is this sort of thing possible in iMovie or Final Cut (I have a mac)? If so, can you please provide some help (or link me to some relevant resources) on how I should go about attempting this, given that I have the two .movs and the .png mentioned above. Again, I am new to all of this, so I am not quite sure what words to search for to locate relevant resources myself. Thank you!
You need to learn about alpha channels. Basically: your "house" video needs to have an alpha channel indicating which parts of the image are transparent; then, you put the "house" video in an upper layer in FCP, and the videos that need to be seen through the window in a layer below it.
Now, how to create an alpha channel for your "house" video? If it's a static image, just use Photoshop and save in a format that supports alpha channels, like PSD or TIFF. If it's a video... the only way I know is using After Effects.
There's also a third way, which is with luma mattes. Basically, you create a greyscale image, where the black parts indicate what parts of the image are opaque, and the white ones which parts are transparent. Then you add that greyscale (the matte) above the "house" video, and change the compositing mode to "Track Matte: Luma". Be aware that I don't remember the exact details here: the matte may be in the layer above or below, and the name of the option might be "Luma Matte"... I don't remember exactly, but you get the idea.