Good open turn video and explanation with some drills: Notice on each turn or drill the swimmer transitions quickly and smoothly with extremely little up-and-down movement. He goes straight in-and-out.
Keep a close watch on where the swimmer is looking during each turn. He never glances backwards! No wasted motion.
Butterfly Video below(courtesy of Michael Phelps and YouTube)
This is the only stroke video here that I would highly recommend listening to. You can mute the others and look at my notes. Bob Bowman (Head Coach NBAC- Phelps and other Olympians) does an awesome job explaining not only what to, but why to do it. Ignore the foreign language, it is in English.
Freestyle Video below(courtesy of Total Immersion and YouTube)
Skip to the swimming at 0:45 if you'd like.
Underwater: Notice the swimmer's elbow and hand position- high elbow, fingertips pointing down. Also notice that he is constantly letting air trickle out his nose. His head is perfectly still, looking down except for some very sneaky breathing.
Above water: Notice the high elbows and smooth entry, finger tips first- there is practically no splash! Again, his head is perfectly still, looking down except for some very sneaky breathing.
Backstroke Video below(courtesy of Ryan Lochte and YouTube)
Above water: Notice Ryan's straight, relaxed arms as he recovers. Also his hand enters just outside his shoulder pinkie first. His legs and feet never stop moving- even rhythm, toes pointed. His head is perfectly still with his chin pointing towards the ceiling.
Underwater: Notice the S-pull! After the hand goes down, he bends his elbow and his fingertips are pointing to the side of the pool. Take a look at where he finishes- DOWN PAST HIS HIPS! As he is finishing past his hip, he is also rotating to his other side.
Breaststroke Video below(courtesy of Kosuke Kitajima and YouTube)
Underwater: Watch the beginning twice. Focus on his pull and head position the first time. His arms press out, squeeze in, and shoot forward. He doesn't start his breath until his hands turn in. The second time, watch Kosuke's kick. Knees are narrow, and his toes are pointed all the way to the side. Once he sets his kick up, he throws the water back!
Above water: Again, notice when to start the breath...as the hands turn in and you begin to squeeze in. Where is Kosuke looking when taking his breath? Where is his head when he's gliding? You can see that he shoots his hands forward and gets into a streamline position BEFORE throwing the water back with his excellent kick.