What does "car crash" mean?

Why does he say "when you're 7 years old" while he's talking about his story? I thought he should say "I'm."

Great question! He uses "you're" to imply that all 7-year-olds do similar things, as though he is addressing everybody who is listening, saying they would have also done the same thing when they were 7. It means the same thing as saying "I did the only thing available any 7 years old would do".

What does "get lost" mean? I thought it means to not know where to go, but in here it used like get out of here. Am I understanding it right?

Yes! "Get lost" in this context means the same thing as telling someone to go away, but in a rude way. Ex: I told that stranger trying to talk to me to get lost.

What does "spring something on somebody" mean? Does it have negative meaning itself?

"Spring something on somebody" is an idiom that refers to telling someone something important suddenly and unexpectedly. It has somewhat of a negative connotation because usually the receiver is stressed that they were told something important without any warning or time to prepare. Ex: My sister sprung on me yesterday that she is eight months pregnant. I can't believe I'm going to be an aunt in one month. Ex: During lunch, my best friend sprung on me that she is getting married in one week and wants me to be in the wedding. Now I only have one week to buy a dress.

What does "car crash" mean?

Normally 'car crash' refers to the collision of cars. But in this context, it refers to cheap TV programs.

What is "wonder by wonder"?

In this video, Aladdin says "take you wonder by wonder" to mean that he will take Jasmine to see many wonders (wonderful things). We can understand this to mean he will take her to see many amazing and beautiful things. This is not a common expression, and but does utilize a grammar pattern [x by x] which emphasizes a succession of things to come. Ex: Read each book one by one. Ex: Day by day, my health condition improved.