Deadlifting with a sumo stance is useful for those with mechanical disadvantages that make regular deadlifting difficult. Sumo is a good way to shorten the stroke of the movement, and can either be used in place of conventional deadlifting or as a supplement to it.
Sumo deadlifting will utilize your hips more than conventional deadlifting, so be ready for your hips and groin to be upset with you, especially when you first start pulling sumo. One of the main benefits to pulling sumo-style is that there will be less flexion and strain on your lower back.
Make sure that your setup doesn't place your feet wider than is necessary. If your feet are too wide you lose a lot of leverage.
A few technique tips:
Experiment with different stance widths and feet angles.
Keep your butt down.
Drive forward with your hips.
Spread the floor with your feet and don't let your knees twist in.
Keep a tight arch in your upper and lower back, driving your shoulders back throughout the lift.
Don't look at the floor like an idiot, look up or straight ahead like Brian does in the video.