I'm using pro version. Works great for me to download high quality. Recently YouTube made changes to the code. I messaged the developer and got this reply:

"A fix is already uploaded to firefox for review and approval and should soon get published and the addon should get auto-updated to v 16.10."

I will wait till update to download again.
Thanks for creating a great add on Dishita.

Fantastic tool for saving those videos, I'm sure there will be an update for the latest browser version shortly.

The support for this add-on is fantastic and it works properly without fail. It is my favorite and first go-to when using youtube. Sadly, when Mozilla or Youtube (Google) make code or UI changes, it hides my add-on so I have to reinstall it with each update from those sites. But the add-on itself is fantastic, I depend upon it almost entirely when I'm online. I'm a Macbook Pro user at home.

Work-around for missing download button (thanks Rosa)
...(display YouTube video page)
Tools > Browser Tools > Web Developer Tools (or ctrl-shift-I)
Inspector (tab)> Search HTML (field)> #eytd_list (press enter)
...(displays 1 of 2)
(press enter)
...(displays 2 of 2. box at right: element display: none)
highlight "none" > change to "block"
...(displays popup upper left with download options)
select an option
...(displays "Save As" dialog)

gd

Just wait until it works.
I hope it won't be delayed to my progress.

Dishita will fix the problem. Just wait dont PANIC..!

hope this makes that easy to use button reappear

Help! The activation button inside the YT window has disappeared!
I have the PRO version and it doesn't work anymore. Damn!

Excellent Add-On It's sad that youtube hates on a good thing. Make the new better than ever. I appreciate you.