There're two ways to embed a YouTube video into a path.
First method is to do it via Assets.
Go to Assets > Create Asset. Under asset type choose "Video content":
As the next step choose YouTube and insert the link:
Finalize the steps. Now, under assets sorting by creation date it's possible to see the newly added content:
Second method is embedding YouTube video via external content.
Go to Manage Paths > Content > Add step > External content:
On the YouTube video click to the "Share" or "Teilen" button below the video. Share modal window will show up. Click on "Embed" or "Einbetten":
Copy the video link exact way as it's shown here (no quotation marks):
Paste the video URL into SmarterPath, hit Save and finish the step:
Now the video should be available in the Path.