Google or look on this site for "Arnold Press" ... same maneuver - different direction. The dumbbells never touch there, and they probably shouldn't when doing this lying on your back either. Continually clacking them together is bound to trigger someone's roid rage. It tells me that the guy in the video, while having a nice chest and abs, has not done much core work, and his balance is off.
The main thing is work on your chest from several different directions (horizontal, inclined, declined benches) so that your entire pecs get exercised. Also, hand placement - a wide grip stresses a totally different part of your chest than a narrow grip. If you keep a narrow grip, you'll get bulk. If you keep a wide grip, you'll get nice wide chest. Mix it up. You'll know pretty quickly what positions exercise what parts of your chest as you try them.
Also consider doing super-sets. Everything you do on your chest, you should find the corresponding opposite for your back muscles. So for example, if you do a horizontal bench press with your hands wide apart, between sets, you should do pushups with your feet up on something so your body is horizontal, and your hands wide apart on the floor - the exact opposite motion. If you bench with a narrow grip on an decline, you should do pushups with your feet on the ground with your hands close together.
Supersets replace overly frequent breaks with exercise of opposing muscle groups. Onlookers will think you are on speed or something, but it produces rather quick results, and is great for your heart!