Kudos to Janine Hosking for managing to make a documentary about a horse who never lost in her career feel genuinely moving and dramatic!
Part of it is thanks to her ability to keep track of the narratives the crews behind Winx's main challengers told themselves as they did their best to set up for proved to be an elusive triumph for them time and time again.
Part of it is her deft touch with archive footage, pausing races at key moments to better let us take in the voiceovers before resuming them to reveal the truth.
Yet, in my eyes, the most important element was the empathy she shows to Winx, with the mindful treatment of the biophysical realities of horse racing. You'll learn a lot more about equine biology than you would have thought possible after seeing this film - from the details of how they are usually born (with Winx being more of an exception) to the toll racing takes on the body. If films are about showing us what we would not see otherwise, then it's unlikely you'll see such footage of a horse being prepared for X-Ray or a surgery anywhere else.
Narratively, the absolute highlight was the decision to withdraw Winx from a key race for the sake of a joint surgery which formally COULD have been ignored for years, "merely" crippling her after she would no longer be expected to win much anyway. That this decision cost a punter massively is just a reminder that betting in such sport is on lives, not just performance numbers.