Please follow below steps to get the ID from your YouTube Videos
If you want to add your own Videos then open YouTube website and log into your YouTube account. If you want to add other videos then no need to log into YouTube account.
From your YouTube account dashboard Right Click on Video thumbnail to get the URL of the video.
You can also right click on any video playing to get URL of the video.
The YouTube videos URL will have one of below format
In first case anything after the last / is ID of the Video in this example ID is fSQXrNn3xV8
In second case anything after ?v= is ID of the video in this example it is fSQXrNn3xV8
If you look closely both the ID are same as we are referencing video of the plugin for example.
Paste all the Video ID into Plugin configuration and your Gallery will be ready.