You're wondering why people like something good?
The reason why people keep on watching this, is because it's good. You got a 7 from me for this flash, and my most honest critique sincerity, which is not uncommon with my reviews, cos I'm honest with all of them, and do not take a bias.
You have a 10 for graphics, because there was the right mix of backgrounds and sprites, while also adding many various details for those who like hunting for Easter egg-like things such as the Espio's Camo sign.
You got an 8 for style, cos you had Amy break character a little, but in a refreshing way, while you had more stereotypicalism with her than was needed.
5 for sound, cos there wasn't enough.
4 for violence, cos of the whole Love Hammer and spikes thing.
0 for interactivity, cos it's a movie. What do people expect with movies, to get 10 in this category? Cos it won't happen, unless you make a CYOA movie, which is classified as a game on NewGrounds.
And finally, 10 for humour, cos I found Tails (My fave character from the whole Sonic franchise) to be good with ideas, and delivering a good performance.
You should try making more stuff like this, or maybe even an alternate ending to this one, where Tails helps Amy to become 16 with an invention, but that's just a suggestion.