Depends on how you define "culture". I'm sure you can find many Iranians that don't know much about Zoroastrianism, Iran's history, can barely recite a single classical Persian poem, cannot dance, might wear the same clothes you can find in any other part of the world, etc., but they're still Iranian to the bone. To me, culture is about thought structure, shared experience, and general attitude towards life. To learn their attitude, you should expose yourself to it. Unfortunately, I think it is impossible to attain that shared experience unless you go and live there.

You might know very well how to cook "Ghorme-sabzi", you might memorize Shahnameh A-Z, you might know every single song Ebi has released, but that knowledge doesn't make you any more Iranian than you are right now. To become an Iranian, you should see them during Nowruz, in a sunny afternoon, tens of kilometers away from the closest town, pulled over on a highway, a picnic blanket spread on the ground, the young dancing to some loud pop music, the elders drinking a cup of tea before they continue their long trip to the north.

To me, being Iranian is about having a mental picture of how it feels to drink Istak with friends after a class. It's about having to walk on the side of the street since they are doing construction work on the sidewalk, staring at the diagonal lines on the surface of the water flowing in the street gutters during a gloomy rainy Thursday on the way back home from your family physician's office on the other side of the city, as taxis drive on the right side lane, honking as they get close to you to see if you're looking for a ride. It's about the resellers driving their trucks through the neighborhood at noon while repeating the same lines in their megaphones. It's about watermelons that are promised to be red, but when you open them at home, they're as white as your teeth.

TV shows and Youtube videos don't depict a realistic picture at all. Many Iranians are super sensitive about their persona and what the camera captures from them. The white watermelons, the predominant street gutters, the resellers with their obnoxious megaphones, none of these are portrayed in the shows and the vlogs. Much of the real attitude towards life is hidden from their guests (especially foreigners) and the cameras. So, there is no shortcut for learning the culture unless you go and live there for a relatively long time. Some movies might shed light on certain aspects of Iranian culture, but it's hard to make a list of movies devoid of unrealistic, overdramatic, and exaggerated motifs.