I think you may get a number of answers from the fitness professionals here–there are many different apps out there and each trainer has a their own individual preference.
If you have a membership to IDEA, then one option is to use Workout Builder to create your workouts and send them to clients. It allows you to make notes on each exercise, and then again when you actually e-mail the workout to your client. I use it a lot and clients enjoy having the videos. Plus, it’s very easy to use.
Others will have more ideas, but I use Workout Builder and have been happy with it.
There are many apps and formats for trainers to use to create videos & pdf’s for clients. Christine definitely mentioned a good one here on IDEAFIT, using workout builder. Another option is to create videos and upload them to your profile and then you can share them with your clients through Client Share. The only issue with this is it doesn’t allow you to send the pdf of the workout. You would have to send that separately.