Beautiful and charming.
I was scouring the portal after having not been too active for a week or so and when I saw a flash with a score of four and a half I felt compelled to view it and see what the incredible score was about. What surprised me was that after viewing the flash I actually felt like it deserved that incredibly high score, unlike many other Flashes in the top flight that are great, but very few of such a great quality. You mention in the description that you have been working on this project for a year and a half, and looking at how much attention was obviously paid to the every detail, macro and micro, I certainly believe that wholeheartedly.
Of course, the first thing to look out for in an animation is exactly that - the quality of art and animation. Right from the outset the art inside the house and the static art as a whole seems nearly pristine, with detail shown everywhere it fits. I liked the fact that a lot of objects seemed to glow slightly in the moon's effulgence that was especially apparent in the early scenes as the character traversed the streets at night. On a partially related note, the coloured luminance of the comets against other objects such as trees was very well done, and the fact that you put thought into every aspect of the animation - I know the lighting of things like the comets and such are a focal point, but nonetheless the amount of thought you seemed to put into them certainly impressed me and I don't think could have been done much better.
In terms of character animation, Jazza's work was high-tier, albeit not quite on a par with the background images and such. At no point did I notice the smooth quality of the animation dropping and the design of the primary character was pretty adorable - especially with the huge eyes and subtle smile that seemed to always be there - although the fact that it was that, always there, got a little bit on my nerves and a bit more variation wouldn't go amiss, in my opinion. The same goes for the alien, whom despite taking a rather different character, with a more sinister feel to him. After seeing him waiting outside the woods I was fairly confident that he'd follow the child in and I ended up worrying in that sense, but after that didn't happen I certainly was confused as to what'd happen - his re-emergence in time to steal the bike wasn't what I expected. Considering he managed to simply get into a hot air balloon and continue on his way right after, I think that putting him in the animation seemed a bit unnecessary, foreshadowing a problem that, when it finally comes, is circumvented immediately, calling into place whether that foreshadowing was really necessary or adds very much.
When you say that this was originally intended simply as a music video then I certainly do agree with you. As the song progressed, as did the storyline in a similar manner, even if it's more abstract than detailed and clear animation at every turn the audio seemed to be fitting, with beautiful piano lines that seemed to be in perfect harmony with every other part of the flash. I think that if I heard it separate from the flash I'd still absolutely love this flash, as it conveys some strong emotions, but I don't think it'd find regular listening without the magic that it being used in such great unison with the rest of this video, which cannot be done if I'm just listening to it in the background, as I usually do with music.
The main shortcoming, I feel, is simply that the plot and such isn't too interesting. Yes, everything about the flash is technically incredible and very charming indeed, but at the end of a day it wasn't too interesting. I definitely like the idea of what I believe to be the dream of a child whom wishes for a particular toy for Christmas, incorporating the likeness of that toy into the dream, but while as a concept it's not bad in terms of being gripping and entertaining it doesn't quite fit the rest of the flash. I agree that music videos usually aren't intended to simply be interesting, but with flashes of this quality I must nitpick.
I give 9.5/10 and 5/5.