How to create a field connector to a sub-key of a meta-key?

I’m trying to create a connector to a post meta key + sub-key. In the below image you can see the meta_key for the LearnDash lesson is “_sfwd-lessons” and I need to connect to the video url within the meta data, key = “sfwd-lessons_lesson_video_url”. How would I set that up in a field connector?