Here are some places that you can get free visual assets from. For video, see further down.

Has Gaphics has sprites and textures for indie developers.

Mayang’s Free Textures, CGTextures also has a bunch of textures.

Open Game Art Free to use and free of copyright.

Clker has creative commons licensed clip art. Good for icons, buttons, and such.

3D models for free as does Archive 3D and Free 3D Models.

Animation rigs can be found at Animation Buffet and Creative Crash. If you know of better places please let me know.

Notes on creating art
So you want to make your own art, eh?

Check out Pyxel Edit for your pixel-art creating needs.

Some resources on improving your art skills:

• Gamasutra has 5 tips for making great animations for 2D games.
• Here’s a great post on Reddit that outlines tools for 2D art creation.

New to art?
For an introduction to making game art check out this discussion on OpenGameArt.org.

For people starting out in the world of art, here are gifs that demonstrate how parallax scrolling works (via this reddit thread):

Click to enlarge and animate.

Click to enlarge and animate.

Icons
Icons are things like menu images and elements of the heads-up display for your game. They are used extensively in RPGs.

The NounProject has simple free icons.

Game-Icons has a good collection too!

Video

If you need video for your project you should check out the Prelinger Archive. They have a large collection of films in the public domain.

Related posts:

1. Game Making Resources