Best answer by Ssherjj
Welcome to the Webroot Community,
I just tried sharing a YouTube video as I run Webroot on a PC and Mac using Firefox and I am not having an issue. Have you tried different browsers? Chrome, Firefox, Micorsoft Edge..etc? Have you checked YouTube Privacy Settings perchance?
If you think Webroot may be the cause then Shut down Webroot SecureAnyhwhere by right clicking in the taskbar and select shutdown and enter the captcha and see if you can share the YouTube video. If so then the best thing to do is Submit a Support Ticket and they will help you troubleshoot this issue free of charge with an active Webroot Subscription.
Hope this helps?