Freestyle: When watching this video, look at the extension, reach, and rotation of the body with each stroke. The swimmers finish the strokes all the way through and have their fingertips pointed down at all times.
Backstroke: First off in this video look at the great dolphin kick Ryan Lochte demonstrates. He keeps everything from his shoulders up still in perfect streamline. His kick comes from his chest down. WIth the stroke you can see the great body rotation and Ryan pulling on the deep water. You also see him not crossing his arms over his chest and they stay in line with his shoulders the entire way and he enters his hand pinky down and exits with his thumb.
Breaststroke: When viewing, notice the timing between the head and feet. Both come up at the same time to display an excellent rhythm. Kosuke is continuously moving forward throughout the stroke, no matter which stage of the swim (whether gliding, pulling, or kicking). Finally, notice the fact that his head is fixed in the proper position at all times.
Butterfly: When looking at this video notice the superb dolphin kick off each wall. Next look at how low he keeps to the water. By staying that low he minimizes the resistance that is normally created when breathing. Also notice how he pulls all the way through his stroke and past his hips. I also want you to look at how he leads his arms forward by putting his head down before his arms come forward. The final thing on this video you need to look at is how with every stroke you see Phelps get his hips up towards the surface and press his chest down.