After installing the addon open a Youtube video page like -
and you will find the "Download As" button as shown in the instructions at - http://www.yourvideofile.com/usage.html , click that button to start downloading the format of your choice.
IF NO DOWNLOAD BUTTON IS NOT VISIBLE OR YOU ARE NOT ABLE TO CLICK IT:
A). Make sure you are using the latest version of the addon, check here - https://www.yourvideofile.org/download.html.
B). If the button is not responding make sure no other Youtube related addon is enabled in your browser. Specially addons related to control Youtube Autoplay are known to interfere with this. You can still use the other addon just make sure conflicting settings are disabled there.
C). The download button could be also missing due to Youtube's experimental layout issue, from time-to-time Youtube experiments design and code changes restricted to very few users. You can try:
- Allow addon to run in the Private/incognito window and then open Youtube videos in a new PRIVATE Window (Firefox Menu -> New Private Window) .
Signing out of your youtube account and refresh the page so any account specific experiments can be turned off, also, try another video.
C). If any of the above does not work, reinstall the addon from here - https://www.yourvideofile.org/
Feel free to get in touch via Support form if you are having problems getting the download working and we will help you out.