Interesting, at 2:20 AF1 reports passing 9,000 for 8,000.
Since that is above the Transition Altitude, the captain should still be on the standard pressure setting, 1013mb, 29.92inches, and report using "Flight Levels", not altitudes.
... not that there would have been any traffic nearby
What I hear is "passing nine thousand for ... for eight zero". A slip of the tongue on the nine thousand, which the stumble suggests he may realize, probably caused by spending so much time in US airspace where the transition altitude is uniformly 18000. I don't know what your experience level is, but when you make as many readbacks as a professional pilot does, they aren't always going to be perfect.
Altimeter settings protect against unintended terrain contact as much or more than they protect against lack of vertical separation between aircraft. Aircraft in a given area are usually on reasonably close altimeter settings, whereas terrain doesn't move out of the way when the atmosphere changes. Traffic is not always the issue.
Just my opinion but I have never understood why this part of the world insists on such low transition altitudes. Wikipedia indicates there is some movement as part of the "Single European Sky" initiative toward a uniform 11000 or 18000. Maybe others will have comments on the history here.