It is possible to convert .flv files to .avi or .mpg files. Many programs do that kind of conversion; I used one a few months ago, but I forgot the program's name. Remember, Google is your friend. However, keep in mind that these conversions are illegal if you don't have the permission, or a license to do so from the copyright holders.
For the copyright part, you'd better ask permission first, be it video or music. Even if you are good willing, by doing that you could be sued by the original copyright owner. There is no angry watchdog like the RIAA or MPAA in Canada, but be careful with what you use.
If you are using a video editing tool that you do not have the license, you could also be sued. You could always use a free software. Some very neat video editing tools out there are free, like VirtualDub. If you paid for software like iMovies or Adobe Premiere, you can use them, but if you didn't pay, you could be in big trouble. If somebody (usually a software company) suspect something about your software, they can ask for an audit of your computer. I had to deal with that kind of issues in a previous job, and I had to make sure my station was clean of warez in case of such an audit.
I know it's for school, but you never know where that video may end. More than a decade ago, I wrote a poem about starving children in Africa for school. I was surprised a few years ago to stumble upon that poem on the net. You never know what may happen to your video. A teacher may submit your work for a prize or something like that. If it stays at school, chances are that nobody will ask you questions, but if it goes in the open, maybe someone will ask you questions. As they say : "better safe than sorry".
You should give credit to people who provided you material (audio or video) and thank them during the credits of your video. If you asked permission first, they'll appreciate that. (Teachers also love when you give them your sources
)
With that, I wish you luck with your project! ;D
