At around 0.13 seconds in. A definite smirk appears on his face and if you watch his eyes, his eyes smile for a moment. It's very brief.
William has had a lifetime of being trained and is experienced enough to know how to skillfully suppress his expression quickly, which he does.
But a quick smile is there.
Why is William allowing a fleeting smile to develop in response to something Andrew says to him? Andrew saw it, too.
Why is he even standing right next to him?
Knowing the press are there? Knowing about the optics?
I don't believe all these reports saying William is trying to get his father to cut ties with Andrew.
Check out this video from this search, prince william looking at prince andrew funeral share.google/XWuCoLMM8wf4Rb1kf