“it went viral”
Go viral means for a post or video to spread explosively, like a virus. Viral is the adjective related to virus. Frank's video became widely shared overnight.
A2-31 / CEFR A2 / EPISODE 31
Sharing news of a popular video
SceneIn Tina's room. Frank rushes in holding his phone.

WORDS & CONTEXT
Go viral means for a post or video to spread explosively, like a virus. Viral is the adjective related to virus. Frank's video became widely shared overnight.
No way! expresses surprise or disbelief. See the note in A2-01.
English counts large numbers based on the million, so 500,000 is half a million (half of a million). Half a million views means the video has been played 500,000 times. The number of views is not necessarily the number of viewers, which is why the later line says so many people.
A monotone is a voice that stays at one level, with little rise and fall. Boring is Tina's word, used to tease her friend. The calm way Frank speaks in his science videos turns out to be popular with viewers, who find it "weirdly calming." It does not mean Frank has no feelings.
"Aren't they scared?" In A1-01, Frank said people run away when they see his face. Here he is surprised that so many viewers saw his face and still want more videos. His joy at the view count turns into surprise that his face has been accepted.
... and all is an informal way to say "including ..., everything." Here Tina reassures Frank: "They like you, stitches included." The next word, superstar, is a light, exaggerated way of celebrating a friend's success.