I’ve managed to make it work as I wanted with these.
initialize
update
Which now results in…

So I’m happy as it updates as necessary.
A change to the colour from white to red for example should make the current video player’s progress bar (which is now using youtube controls) change. Only thing is although the data object is now updating, the player controls doesn’t. It shows red if I specify it directly in the initialize section but doesn’t reflect the change in the update.
I’m sure I’ll figure it out, maybe a cache issue or it needs reloading or something.