Works fine now! Puntuado con 5 de 5 estrellas

Version 0.6.7 works fine. Excellent add-on.

Esta valoración es de una versión anterior del complemento (0.6.5). 

Thank you for feedback, but sorry i cant confirm this. This youtube feature working fine for me with latest Firefox and latest addon (0.6.7). Make sure you are using latest versions.