IS IT ANTISEMITIC TO QUESTION ROTHSCHILDS?

UK Labour Party leftist group "Momentum" launches a video attacking "conspiracy theorists" arguing it is not only a fallacy to claim the Rothschilds have any influence on world events (they are quite poor really !!!) but that it is actually "Anti-Semitic" to question their motives or mention them in any negative light.

https://twitter.com/PeoplesMomentum/status/1101143739588923392