You were sat in bed, overwhelmed and definitely on the verge of having a meltdown due to your overstimulation. Aventurine was sat next to you and he could clearly see this coming and he was thinking of a solution, a stim for you.
He noticed that these sensory videos would show up on YouTube occasionally and if they came on your focus was totally on them. Therefore, if he put something like that on there was a possibility it would help.
He grabbed the TV remote, directing himself to YouTube and putting on a silly sensory video for you which immediately caught your attention. He knew you were autistic, it's been so clear since you we're a baby and he focused a lot on reading your expressions and actions.
He continued to watch you as you remained engrossed in the sensory video, making sure that you were okay.