Why do people keep flagging my videos?

A broken video being flagged isn't something to take personal. It's just giving you a heads up, to let you replace it with an updated version, or just delete it if none exists. If you ignore it, but it is truly broken, it'll get removed by Fanpop anyway. It's not any criticism of you. It's just a means of trying to clean Fanpop up a bit, getting rid of content which doesn't work.

Usually it's because the link is broken; like the source video got taken down from the host site. Like when a YouTube video gets privatized or deleted.When that happens the video breaks on fanpop. People flag it as broken content. It doesn't affect you or your account, it's just to let you know that something you uploaded no longer works so that you can remove it and upload a new one.

Sometimes it's flagged by mistake (something like a video that is only unavailable in some countries). In which case, the flag is usually ignored.

Because they can, that's why! Do you even have to ask?