I think that we should differentiate two things in your post. 1. The Media. 2. Youtube channel subscribers.
They maybe related, but I think different platform have different problems.
Now for my casual observation, Tibetan buddhism and Zen buddhism is more represented in western films. But they are only superficial. I think it is more of what they are associated with.
Zen is associated with eastern martial arts. Many traditional martial arts from Japan and China teach philosophy that is influenced by Buddhism. Even the Bushido (way of samurai) is influenced by Zen.
That’s why it is easy for action movies to feature Zen, as part of character martial art.
Tibetan buddhism, is perceived as mystery. Tibet is located in arguably one of the corner of the earth, so it is easy to imagine that it hides some secret within. Whether it was treasure, treasure map, secret knowledge, hidden paradise shambala, magic…
The exotic thangka and art and ritual enforce this perception.
This is why it is easy to make a plot around Tibet and Tibetan buddhism. In Ace Ventura 2, the protagonist went to tibet to learn something from the monks before the film start.
The Sorcerer Supreme from Dr Strange/ Avengers is arguably based on Tibetan buddhism.
Also, Tibetan monks create their own movies to better represent their own culture and religion.
But I think average people would not know deeper than the outer package. They wouldn’t know that Vajrayana has thick commentaries explaining the philosophical tenet, or that meditation to observe the mind in natural state. Or that Zen need one to sit for hours doing nothing…
While Theravada… I failed to find what popular thing it is associated with.
No martial arts, no tea ceremony, there is magic but it is only known in thailand produced movies, only some monks meditating silently in forest…
I am not sure about youtube situation. In my case, since I actively search and subscribe any good buddhist channel. There is Ven Sujato, Amaravati, BWSA, Ajahn Sona.
Not sure about sadhguru, never listen to him (false guru from false religion why listen). But I have seen some of followers comment. What I perceive is that his philosophy feels good, mysterious, and affirming soul/self.
Compared to (Theravada) Buddhism with dry and boring themes such as not self, suffering, impermanence… I see why it is not popular. It just cut straight through the important matter, but people are uncomfortable with the truth.
Edit: Also, I have seen some with clickbait titles
“This is how you supposed to meditate”
“The Guru explain meditation you can master in one hour”
Usually respected teachers don’t do this. Though I have seen some local Buddhist channels doing this, but I think it is not sanctioned by the teachers they feature.