Hi Anamaria,
thanks for your reply! If I do as you suggest, I should put “Standard” as the default post format in writing settings and change the post format for each post, but as I already said I want to keep “Video” as the default post format because the client wants to publish only videos, so unfortunately this is not the ideal solution. The default post format should remain “Video” https://imgur.com/a/H5u8ecR

Now, with video as the default post format, when I create a new post, a video block automatically appears and each time the client will have to delete it manually, because the video URL will not be entered there but rather in the Featured Video field, as in the image https://imgur.com/a/tpDtH4D

P.S. I noticed that the video block appears automatically with each new video-post only when the tagDiv Composer is active.