Be careful with old versions!
These versions are displayed for reference and testing purposes. You should always use the latest version of an add-on.
Now works fine again.
(*) Added support for SeaMonkey 2.23 .
(*) Fixed jQuery conflicts.
(*) Added Chinese language.
Next to each video in the list (right hand side), there will be a small arrow, hover that arrow to open that option, click on "Copy URL to Clipboard' to copy the URL link to the clipboard.
(*) Added support to SeaMonkey 2.19.*.
(*) A fix for SeaMonkey.
(*) Fixed button location (due to changes made on YouTube).