A picture is worth a thousand words.
Video feedback allows a coach to talk less and the swimmer to connect the feel of what they think they're doing to what they see.
I use my iPad every day during practice and lessons to show swimmers what they look like when they're working on a new technique, or for before-and-after views of a stroke change. I use it with our beginner swimmers to encourage them and let them see themselves, maybe for the first time... "What do you see?" I ask them. "I'm awesome!" they say. They are so right! Older swimmers will pick out things they need to correct all by themselves. I focus on praising what looks good.
Ubersense has an iPad app that I use. Video is easy to take, play frame by frame or slow motion, draw circles, lines and angles, and compare side by side with another video. I can email or post a video to a swimmer so they can watch it when they get home. I can VoiceOver and record my comments, Ubersense is free. http://www.ubersense.com/
Coach's Eye is another very similar iPad app which costs $4.99. This app has the same capabilities as Ubersense.... slow motion, drawing on the video in colorful pen strokes, voiceover comments. http://www.coachseye.com/home/purchase
Are you using another software that you like?