Video won't load

I’m using a popup button. When I check the box to use Lightbox on the edit page, the screen pops up with a message saying the video won’t load. When I uncheck the box, the video comes up on a full screen. the video is from youtube. What settings do I need to change to make the video load in the smaller screen?

https://ww.wp.xz.cn/plugins/lightbox-plus/