Currently it is not possible to functionally add video links to a cms template via the cms api.
It is necessary to click through the web ui and edit the field with the video link, to enable the embed. For bulk operations this is a horror scenarios, which has affected users in the past.
This bug or limitation has been around for years. Last year or so somebody finally said that they are looking into fixing this issue, but unfortunately there has been no feedback since.
Are there still plans on fixing this? It would be immensely helpful!
And there was another one, the link to which i have lost.