Many Thanks for a great plugin.
There appears to be a tiny conflict with Buddypress Activity Plus.
With your plugin active - links added via "Add Image URL" in Buddypress Activity Plus are not uploaded for some reason. (no problem with Uploads from remote computer - problem only with links)
Deactivating your plugin-the problem goes away.
Have tested this on clean local install with only those plugins and Buddypress active.
Any workaround much appreciated.
see previous report - http://wordpress.org/support/topic/add-photos-videoslinks-button-not-working?replies=7