For this set, we set up our underwater video camera in the end lane. Swimmers performed the 15m fast underwater kick in that lane. They watched their video on a time delay on our flat-screen TV and then did the 5 x 25, one in each of our 5 remaining lanes. We repeated this circuit for 30 minutes.
This could obviously be easily modified to look at any stroke or any technical aspect in that first 15m.