I'm not sure what those links are that you're using, but we tend to use the embed code. However, you need to be Premium for that due to the character count.

You can try the actual url, or copy the share link and see if either of those work.

As I say, it's the embed code that a lot of us use and seems to work ok (right click on the video and it's one of the options)

And you'd paste that straight in the Thread box, not as an image.