I am using lectures I have created on Camtasia and uploaded to screencast to teach students in my class. Is there a way to identify and ensure that each student has actually watched the videos?
Screencast has an option where you Edit the folder that contains your video(s) and then toggle the site Privacy to "Authenticated" and then invite the students by entering their email addresses. If they accept the invite, you can see their email address under Accepted Invites. Doesn't mean they watched, just accepted your invite. Absent that, you would need to have your own website where students can log in and only after logging in, find the link to the video(s). And, when they click to watch the video, to capture the fact that they did that. I would suggest a more rigorous method is to just email all of the students a couple days after they are supposed to watch and ask, in your email, "In order to recieve credit, please comment on the topic at 3:05 in the video".
While not a feature of Screencast, this is a feature of TechSmith Relay. If your school finds enough value in this, they may want to invest in Relay for your school. It also integrates with your LMS and has other options to help your teachers get more videos online.