"filename must not contain illegal characters"

Thanks for the update, now working again in Firefox.

does not work, "signatureLocal" message etc. Being logged in changes nothing.

Error: "signatureLocal: Signature cannot be verified". If you're getting this error you will need to update the plug-in. You may need to login to Google (owner of YouTube) also. Formerly, just logging in to Google was enough. Then it wasn't anymore for me yesterday. On the June 13th I downloaded the update for this plug-in and it worked. I was already logged into Google and I don't know if that's relevant. Good luck to you! It is a great plug-in when it's working!

good

Stopped working recently. Any file I download from YT stops immediately.
Besides that, it is a nice addon based on ffmpeg.

This extension unable to download certain videos.

Best extension for get original files from YouTube.

very good

exelente !!!

mantul

the best downloader I've used I really like all the available options and the speed that the developer updates

Quite strange that it has been unable to download certain videos as of late.