Without watching the video, it's the broader appeal of RE always being on the more action-y, campy side of Survival Horror as opposed to Silent Hill, even with the first three games. As someone who normally hates horror, I love RE because it gives me the opportunity sooner or later to shoot whatever's chasing me in the face.
Also, the setting itself is unique in that it's both somewhat grounded than the usual SH (as magic viruses work in place of supernatural forces) but also can be worked with in so many different ways. The Racoon City incident didn't end the world in a zombie apocalypse (no, the movies don't count) but it did let cat out of the bag and now both governments and NGOs alike can unleash unspeakable horrors in any part of the world. It's how we got from standard zombies to werewolves, ogres and dragons in 8/Village. Even within the classic trilogy, you go from just shooting zombies and mutants in a mansion in 1 to running away from the love child of the Thing and the Terminator in 3.
Ghosts can't beat zombies