Enjoy!
Glad to see a new bentacular tutorial 
It’s been a while.
I used that clip to test your method. It’s a good thing you mention to experiment with different blend modes.
For me, with that Light Leak clip, the Add blend mode works best. Screen also work well.
Great! Sometimes the background of the source videos determine which blend mode I’ll use
Great video and nice effect, It inspired me to dive into the effect of blend modes and created this video.
Awesome!