Put in the Central Asset Manager and see if that does the trick.
Thanks, I was only worried not to have too many elements in the asset library. Do you know if it can be safely deleted from the asset library after attaching it in the courses? 
Good Morning,
Feel free to use your Asset Library freely. I loved using the Library any time I planned to use an item more than once.
If you are going to use that Asset in multiple places I would suggest keeping it in the Asset Library. In the future, if you need to use that asset again, you can pull it from the Library, ensuring consistency throughout your content. In addition (and my personal favorite) if you need to update that asset, you can update the asset in the Library which will then push the updates to any location that Asset is located.
Alternately, deleting an asset from Asset Library will not remove the contents from where it is placed. The asset will continue to appear in content, but will no longer be linked to the Asset Library.
Heads Up: Items deleted from the Asset Library cannot be recovered. Please use caution when deleting.
Happy Friday!
Karen