OK what I want to do is create a workout to match a load of music videos, alternating between going hard for a song then recovering for a song.

This will require two things, first I need to join the music videos from my itunes collection into one continues mp4 video. I think I will just need a suitable piece of software, preferably freeware.

Then I need to create the workout to match the timing of the videos.

Anyone have any idea how I might go about this?

For the workout you can download the trainerRoad workout creator DETAILS HERE

Can’t really help with the music part of the question. I’d use Adobe Premiere which I occasionally use for work (and that is available on a free one month trial download) but there are bound to be more appropriate and free options available to you.

TrainerRoad have just released an updated version of the workout creator which on first glance seems much improved.