Quantum computing explained in a 2-minute video
by Mark Frauenfelder from on (#42M1W)
If quantum computing becomes practical, it will be able to crack encrypted data in an instant. Forbes has created a good two-minute video that gives a high level overview of quantum computation.
If you want to know more, Simon Singh's fantastic The Code Book gives a much more in-depth (yet still easy to understand) explanation of how quantum computing works. I can't recommend this book highly enough.