Got some tricks

Zorro, You’re saving it as a movie maker project and not as a video.

Instead of choosing “Save Project” or “Save Project As”, you need to choose “Save Movie”. Then, select from the menu what size you want. I would recommend “For Computer”, as anything smaller might sacrifice too much quality, and anything larger would probably take too long for people to download.

Yes, I do have movie maker. Once you finish the project, do as Fishmonger says. you have to export it, so that it turns into a playable movie file, not a movie maker “project”. Think of it like this: saving it as a project is like saving it as a word file. But exporting it is like printing the file. Kinda.