Windows Movie Maker still works on Windows 10. However, you can't just install Movie Maker, you have to install Windows Essentials 2012, as it's a part of that suite. You used to be able to download it here:
According to that post though, the download links were removed because, "Update (3/21/2017): URLs removed as WLE lifecycle is over."
If you don't trust download sites, since they are usually trying to blast you with ads, get you to click on the wrong link, or attach a download manager (or whatever), you can find it with some basic google searching. However, here it is from web.archive.org, which was saved from Microsoft directly: