Before trying to replicate the skills and drills featured in these video clips, it is important that your talk to your coach to work out what is best for you and then practice, practice, and practice some more.
It is important however that, in preparing to swim medleys, you work on your weakest stroke.
Also critically important is to work on your turns. Here is a video with Stephanie Rice swimming and her coach Michael Bohl taking you though the critical features of medley turns. It is also worthwhile carefully watching Stephanie’s swimming technique.
It would be a tough ask to ask a masters swimmer to emulate the number of underwater dolphin kicks, except of course in breaststroke, that Stephanie does. Talk to your coach to work out what is best for you and then practice, practice, and practice some more.