Can someone tell me what I did in the node editor??

I know, it’s a weird question. I’ve used maya for a while for work and then just recently tried Blender. It’s awesome. I think it’s much easier to use and has comparable outputs. Anyhow, I decided to teach myself motion tracking and trying to light an object with indirect lighting. Here’s what I got:

Like the caption reads, this was the desired effect that I wanted, but I’m still left with a question. I used a picture of some skyscrapers and the sky as the world texture so my text has that reflection. But when I would render an image, the pictures of the skyscrapers were there and you could not see the video underneath. I found an old version tutorial that showed me I could replace that picture with a solid color. Then I tried black and blending with the video using Add - but that removed all the black from my object making it transparent light blue.

So I played with some nodes and I think I made somewhat of a luma matte like in after effects and applied it correctly, but I’m wondering if there is an easier way than this or if this is just wrong:

Thanks! I’ll have tons more questions.