Superficially, this is just a random video of someone throwing french fries and mayo at the Prime Minister of Belgium:
Delve a bit deeper, though, and you really have Belgian politics in a nutshell right on this stage. Belgian politics, after years of deep political crisis around language issues, has temporarily re-aligned itself around economic subjects. And that's what this incident is all about.
Belgium is deeply divided between its French-speaking and Dutch-speaking halves, and for a long time the country the rise of a new Flemish (which is to say Dutch-speaking) nationalist party, the New Flemish Alliance, paralyzed the country. Earlier this year, for the first time that Flemish nationalist party entered a governing coalition at the federal level. Historically that hasn't been possible because the French-speaking parties wouldn't collaborate with the Flemish nationalists. What's new is that Charles Michel (the guy pelted with fries in the video) decided to make an exception to that rule.
Michel runs the Mouvement Reformateur (French for reform movement) which is a Francophone free market party. He agreed to lead a coalition government that includes the New Flemish Alliance provided that the government focus exclusively on economic issues, rather than constitutional and linguistic ones.
Since the Flemish side of Belgium is richer than the French side, implementing a free market economic agenda tends to be objectively pro-Flemish. Consequently, the coalition math of Francophone free marketers plus Dutch-speakers works. But it rocks the boat of Belgian politics, and is very upsetting to the majority of French-speakers. Which is how, in a nutshell, you end up with the Prime Minister of Belgium having a speech interrupted by a protestor throwing food and shouting anti-austerity slogans in French.