Hi @Philson I know its tagged "resolved" but like you said the solution isn't included. I recently had the same problem when updating the plugin version. Everything going fine till poof link connected straight to vimeo. I went through all the default checks no plugin conflict, code was correct, you know all that stuff.
I got it back up in running. This is how it worked for me:
• Uninstalled WP Video Lightbox
• Downloaded the current version of it
• Uploaded the .zip file and activated it
Lightboxes are now back to working just fine. (Im sure you are fimilar with uploading a plugin, I just think its nice to be thourough)
Hope this helps