[Help]Why these accounts has so many views than their followers?

Hello BHW friends, I've seen many accounts(personal/3~5k followers) sometimes has a post(video) has much more views than their followers. For example, these accounts has followers like 3~5k , but suddenly a video has 30~50K views. As they're personal accounts , seems they didn't do any promotion with their post, just the post goes viral, the post is just a life video which I think is not same "viral" video as I see in some pages. I don't know how does this happen, any info can share?

I even…

[Help]Why these accounts has so many views than their followers?