Troubleshooting YouTube URL trim/delarg

Hey crew, I'm having some unexpected trouble trimming a url. Here is a 2-min video. Thanks for any help!

Here's the quick video: https://www.loom.com/share/716fa398ffbb411694d8c9ce4d108614?sid=4819d5b4-e439-4281-beb9-3b30d8b0bfa5