With a video tape this isn't necessary, since I can see that you are performing. With an audio tape, there would be the possibility of having someone else do your performance for you, so I couldn't know the integrity of your grade.
If you haven't yet chosen your instrument and/or song, and you'd like to use your computer and the internet to solve this, you do have some options. Take a look at the Links page of the course web site, and you'll see a section called Online Music Learning. There are links there to some free online learning sites. For example, you could use the World Rhythm Training link to a page which will teach you two African polyrhythms. These can be learned online and don't require an instrument. You can use two pencils (or chopsticks, etc.) on a desk. The site gives you MIDI files to listen to, and instructions. If you learn the two African polyrhythms "How to Play Two Against Three" and "Eve Bell Pattern with Clap" you can use them as your performance.
There is also a Piano on the Net site which gives free piano lessons, and you could work your way through the Starter Studies to help you play a simple song.
There is an Online Music Lessons site which gives lessons in recorder and whistle, and there's the Online Guitar Lessons site, as well. Look at these and see if you could learn a song!
Check these out and get back to the MCO-L list to let us know what you think of them.