Anybody can submit Flash animations, GIFs, and some types of downloadable files. The special case is video files.
If you want to upload .mov, .mp4, .wmv, .avi, dot-whatever video files, you need to apply to DeviantArt's film community.
I repeat, here is the link that explains everything: How do I become a submitting member of the film community?
It doesn't cost anything. I applied with my animation Cyn Wolf: Down and got in that way, so the quality doesn't have to be spectacular, but it should be decent. When I applied in 2009, it took 4 months for them to process my application.
Before you apply, note these special rules for submitting videos:
- You cannot use copyrighted music. This is why my DA videos sometimes have different music than the YouTube versions.
- You cannot submit music videos or AMVs, unless everything in it is your own original video/animation and you have permission to use the music.
- You can use royalty free music. Remember to give credit if you do.
- Your film/animation has to be at least 10 seconds long.
In short, only apply if you are making your own original animations or videos.