Detecting plagiarism from videos

Hello all. I'm an ESL teacher at a small university in South America. Currently we use Urkund to find plagiarism in writing, but one of my fellow teachers made an interesting discovery from one of her students the other day. The student in question could barely string a sentence together, but the student submitted an almost perfect final paper. At first we thought that someone else wrote the paper or the student purchased it online. However, when confronted, the student confessed to copying the paper from a YouTube video. Basically, the student transcribed a short video on the topic and submitted it.

Have you come across this problem before? Can you think of anyway to catch this sort of plagiarism without reading it and just realizing that it isn't the student's work?

Any suggestions would be appreciated