Due to the way in which Blackboard works it can sometimes be problematic linking to non-secured external content. Not all web browsers deal with this issue in the same manner which also makes it difficult instructing students how to access the content. To remove the issues at source we suggest the following:
Flickr, SlideShare, Youtube
Use the Mash Up tool available in the Build Content menu.
If adding a link via Build Content -> Web Link, make sure you set Open in New Window to Yes
If adding a link via the content editor, make sure the target is set to Open in New Window (_blank)