One hell of a bad example for her kid.
But we should keep in mind that we didn't get to see what happened immediately before the video started. From what the aggressor was saying, it sounds like she believes they were "talking shit" about her. Does she have a good cause to believe that? We don't know because we didn't see what happened before. I do agree that it's incredibly rude for two people to speak a language that a present third party does not understand, and especially when it's a non-official language in a business setting. I've been in situations like that through my work, and even though I was quite sure they weren't "talking shit" about me, it was still irritating.
Of course, even if she suspected they were talking about her behind her back, none of that justifies the woman's outburst.