Very cute
This was well done. I'd yet to feel such a foriegn feeling while watchig a flash animation as I did when the ghost girl stands frowning. You begin to ask, "what is really going to happen?", thinking in someway the boy will meet his untimely demise. That makes for a good movie, regardless of style. Not often in this predictible world do we face such uncertainty in film.
The music you used, though creepy, fit the mood and overall ending. It was as intriguing as the video, to tell truths. Though the music was infact somewhat happy, it didn't let you forget that the boy was still playing with a ghost in the middle of the night.
As for things to work on, try to keep in mind that when dealing with the inside of a house at night, there are extreme shadows masking bits of the rooms; created by moonlight, street lamps, etc. That's what makes an empty house at night so...well, creepy. It would've also helped accent the young ghost's glow.