They say that if we use two entangled photons and let them fly far apart, then pass one of them through two filters, and the second photon through the middle filter, the first photon will be affected - it will get a chance to pass though the pair of filters.
That they say is "spooky action at distance" - the second photon will influence behaviour of the first photon at the remote site of the experiment and the "influence" is faster then the speed of light.
Example here by MinutePhysics and 3Blue1Brown: https://youtu.be/zcqZHYo7ONs Explanation about entanglement starts at around 8:50.
But even with that addressed, to me personally this video is not satisfying.
If the spooky action at distance can be observed so trivially - choosing a filter at one site site affects what happens at the remote site - we don't need a mathematical inequality (the Bell's inequality), it's already so obviously spooky.
There are also serious problems with clarity of their explanation, as I commented in https://www.youtube.com/watch?v=zcqZHYo7ONs&lc=Ugz3tzpDP_i1N... and https://www.youtube.com/watch?v=zcqZHYo7ONs&lc=Ugz3tzpDP_i1N...
I am not sure the real Bell experiments are really done using 3 polarizing filters and will the effect really be observed in experiment with two remote sites.
My conclusion, it's problematic to rely on "pupular science" explanations, even by good channels like MinutePhysics and 3Blue1Brown.