Multiple illusions in this video showing 10 optical illusions in 2 minutes (about) –

And to get an idea of how the flat-becomes-3-D works, this video shows a flat board that appears 3-D until you look at it from the side:

This clip is less than a minute long.

And more optical illusions in this video, including some 3-D chalk drawings:

The 4-min video has dozens of illusionary art examples.