When I send someone a share link to a video on screencast, they also get a "share" arrow which allows them to copy the link (or embed code) and send it to someone else. How can I prevent viewers from sending my video links to others?
If you are a Pro user there is an option to hide the 'Share' button by using a custom view page template. If you are a Free user the only way to hide that button is to set the privacy of the folder or playlist that contains the media to Access Phrase or Authenticated.
I should note that even if the button were not shown for Public or Hidden content it would still be possible to simply share the URL the user is visiting in their browser. If you are concerned about who is accessing your content then I would suggest one of the other privacy settings.