When i try to upload a video...?

from windows movie maker, it says it is an invalid file format. how do i fix this???

how do you change the format?

there is a very simple way tht i tried wen tht happened 2 me.wen u go 2 the "upload" thing,on the right side panel there should b a thing tht says "use multi-video uploader" and do the stuff.it worx really well so yah tht should help k thnx bye! dont ask me y i said bye

I have the same problem, I think you need to just change the format to something like jpg.

Alright, this is a very common mistake that people new to youtube seem to always make. What you need to do is instead of saving the file normally, find the publish to my computer or finish movie or a button like that. That button will save it as a file type of your choice, AVI, WMV and a few others. AVI and WMV are both accepted by youtube. This should solve your problem.