Could you just tell me what URL should I add in allowed iframes in order to have the video shown as you did? It would perfectly do the job for now, even if it’s tall indeed.
As for the video height, it’s possible to make it less tall by setting a max-height with CSS on the iframe. The issue is that the iframe has no attribute of any kind that specify that it’s a short (vertical) vidéo.
But then, what should I do in order to make the video appear?
If I write in my post https://www.youtube.com/shorts/SWeTMdyv50Q, it won’t work.
If I write <iframe>https://www.youtube.com/shorts/SWeTMdyv50Q</iframe>, it won’t work.
If I write https://www.youtube.com/embed/SWeTMdyv50Q, it will work, but will display the short video with standard youtube video width/height ratio (which is OK for me, though I’d prefer having another ratio and not having to manually write “embed” in the URL):
Also, replacing /shorts/ by watch?v=, the default URL of a Youtube video, works.
So, in youtube, on https://www.youtube.com/shorts/SWeTMdyv50Q, doing right click → Copy video URL will work since it returns https://youtu.be/SWeTMdyv50Q which is correctly displayed on Discourse (with the regular wide ratio though).