Somewhat aware of the problem. I expect it's with the size of the files or timing out of the request with the upload. The site was developed just as a quick project to test out bitcoind integration and I didn't expect it to become the only btc file hosting service that seems to still be around. What happened to the others?
There's currently a max filesize upload limit of 2mb and a maximum timeout of 300seconds(or 5 minutes). If either of those are exceeded then it will fail.
Well that explains why my students have been having so much trouble with it.
Is there any way to increase the file size to something more significant, if you need more disk space I'll gladly forward some btc to help cover the initial costs.