For some reason, when browsing YouTube a click on the webcam symbol in the URL bar adds the previously watched video to Zotero, not the currently watched one.
I can't replicate that. There may be some problems with the YouTube translator (they change the site all the time), but we'd need exact steps to reproduce, including URLs.
"Works" for me with any youtube url. for example
https://www.youtube.com/watch?v=AnDagpv4kUk
If I watched another video before it will add the previous to Zotero. I have to click reload in the URL bar to make Zotero actually add this link.
Zotero 4.0.25.2 in Firefox 37.0a2 (2015-01-16) on Linux Mint 17.1 Cinnamon 64bit
I can see if I can reproduce this, but generally beta and alpha versions of Firefox aren't supported (and at a minimum you'll need to mention you're using them when reporting problems). Zotero is currently compatible with Firefox 31-35.
Upgrade Storage
https://www.youtube.com/watch?v=AnDagpv4kUk
If I watched another video before it will add the previous to Zotero. I have to click reload in the URL bar to make Zotero actually add this link.
Zotero 4.0.25.2 in Firefox 37.0a2 (2015-01-16) on Linux Mint 17.1 Cinnamon 64bit