Having said this, I do remember a time when I used Moodle to give an exam in class. At the beginning of class I told all 40 students to login to Moodle and begin their exam. I had a small hosted server at the time, and it actually took two to four minutes for all 40 students to get logged in. But then my Moodle was fine.
So if you had a similar situation with 200 students, maybe they would all be "concurrent."
My bigger concern is with your videos. I used to have my videos on the same server as my moodle. I had to move them to a separate server because my Moodle was slowing down when students were streaming my videos. There might be some server-side settings to alleviate (or tweak) this problem, but I am not that skilled of a "server" admin. I am just a professor.