Great responses, thanks.
Replies:
Series marking is FH T780, I hadn't moved the garmin speed sensor enough.
It is smooth and working OK, I discovered the characteristic as I was cleaning the bike with the back wheel off and not as part as a fault investigation.
When I took the original video I hadn't got any tools out. I have since checked the lockring and it was tight. I got my chainwhip out, removed the lockring and pulled the cassette off.
The freehub is tight on the hub, the play is taking place across the bearings of the freehub as can be seen in the second video below. Whether this is excessive of not is what I'm seeking opinions on. My brother has the same bike and same age so I'll get him to check as well. I'm more interested in reliability than chasing warranty to be honest.
Axle seems fine, there is no play on the wheel bearings and everything is smooth. Just the play on the freehub to bother me.
View: https://youtu.be/FQUd7s4Q6K0
Its a long time since I replaced a freehub but the ones I have changed were all on mtb's that had been caned in sandy conditions.
Oh, and I'll check some of my clubmates bikes on Thursday - they are mostly on tourers too.