i have a footage showing office's screen which displays some statistics, etc.
I masked out that screen and added a different footage within mask's boundaries and now the screen displays some football match instead.
Now i want to add another footage right after football footage - to imitate switching between tv channels (i guess it's also called channel surfing?). In other words, i want that screen to display a football match, then some news report, then some documentary, etc.
So i added 2nd footage to may composition and placed it under football layer (refer to printscreen)
I selected football and 2nd footage and made a precomposition. then applied Alpha matte and set track matte as parent. Did not work - only a white rectangle was displayed instead of footage.
Then i tried to duplicate track matte and placed it right above 2nd footage and set it (track matte duplicate) as parent - was thinking that each new footage may require separate track matte. did not work either...
By the way, i managed to display 2nd footage by applying Alpha inverted matte and setting it as a child to track matte, but its not quite right because i have to meticulously adjust 2nd footage's size manually to fit into office screen's frame and its really hard to do
A Track Matte only works on the layer IMMEDIATELY BELOW IT. In your screen shot, you can split the original track matte layer, move it just above your 2nd footage layer, and things should be good.
did as you said - it works!