You can find any web address in the so named address bar atop of every webpage. For this thread on our forum this would be:
https: //cassiopaea.org/forum/threads/how-do-i-insert-articles-pics-videos-into-my-posts-on-my-laptop.50776/
For the Mozart video in the above example of Natus Videre it is:
https: //www.youtube.com/watch?v=Rb0UmrCXxVA - as shown on the right of his inscribed number 2: Enter Media URL.
After you have entered the correct web address at the proper place, you
still have to press
Continue (to the right of his number 3) to make the desired video really appear in your post.
In the post box you will see the following:
[MEDIA} https: //www.youtube.com/watch?v=Rb0UmrCXxVA [/MEDIA]
but without all the spaces. I've put them in now to make you see what it looks like before posting. Would I have not put the spaces in here, the Mozart video would have appeared once more.
After that, you can either
Preview your post to check whether the video is where you want it to be, or push
Post reply directly for the same result.
When it's not as you want it, you can either correct it right away (after deactivating
Preview first by clicking on it again) or via the edit button at the bottom of your post. Remember, the edit window is limited to 10 minutes after posting.
Hope all is clearer now and good luck with trying again.
You will get the knack of it once the first one has succeeded. I'm sure !