How to Achieve Titles

Hi all,
I’m trying to create the following but unsure where to start.
I would like to add a title to my clip. Rather than the title be a solid colour, I would like the letters to be made of another playing clip - so that it looks like a clip is playing inside the letters.
Any ideas how I might be able to do this? I assume it’ll involve clipping of some sort?
Many thanks in advance.
I’m trying to create the following but unsure where to start.
I would like to add a title to my clip. Rather than the title be a solid colour, I would like the letters to be made of another playing clip - so that it looks like a clip is playing inside the letters.
Any ideas how I might be able to do this? I assume it’ll involve clipping of some sort?
Many thanks in advance.