Or at least I hope this display of Breton nationalism is the real thing, in light of the popularity of various fake nationalisms which seem to see multiculturalism as compatible with their particular national allegiance. (The SNP, Plaid Cymru, and Sinn Fein come to mind, with their inclusive 'one country, many peoples' attitude).
The best-known Breton, for many of us outside France, is Alan Stivell, who despite his love for his Breton roots has sought to blend 'world' (read:Third World) influences and African performers into his music. I don't understand this contradiction, but then liberalism makes no sense.
And I don't know how typical Stivell's attitude is toward his ethnic allegiances.
In any case I hope this incident of assertiveness is a sign of a resurgence of a real ethnonationalism. Accept no substitutes, as the old advertising slogan said.
Note: the video of the incident is here, or should be; I could not get it to embed.