Before I tell you about some of the other things I've noticed, allow me to make a statement about the tutorial. First off, it was after about 50 hours of sleep deprivation that this video was made. Secondly, these are merely MY first impressions on Sonic's moveset. I do not claim to be a "pro" Sonic player who knows everything about his metagame and whatnot. I am a Sonic fan. The first game I owned was Sonic 2 for the Genesis and have been in love ever since. This video was made on a whim with the purpose of showing people who haven't seen Sonic's full arsenal of moves and some strengths and weaknesses of his attacks.
That having been said, I played the game quite a bit more today. Tried some of the stuff you guys mentioned. Uthrow to utilt doesn't work well from what I've seen. Only got to use it at 0% a couple times but I tried it several times at very low % and it didn't seem to work. As soon as you uthrow, they can just DI to the left or the right and avoid it. I didn't really get a chance to try it more than about 20 times because of the time crunch we were in, so maybe I missed something.
I did notice that At around 50% I did an uthrow on Pit and followed with an uair. This did in fact seem to be a truly unavoidable and devastating combo. Very difficult to pull off successfully however. I also tried chasing them high above the level with up b followed by uair. It successfully killed three people that night, and at low % I might add. But as soon as my opponents saw me get a couple kills with it, they never let themselves fall for it. It seems like it might be able to catch people off guard occasionally, but pretty much as predictable as a falcon punch.
My opinion of his neutral B is the same as always. His recovery is so amazing that you might as well not bother using moves like neutral B and side B as recovery and instead use them to catch your opponent off guard. To the untrained eye dsmash, side B, and down B look like the same attack could try using that to your advantage.
And in response to emblem lord, from my current knowledge, you cannot dash to down smash. I really wish you could and often find myself attempting to dash to dtilt only to be disappointed by Sonic's dash attack. I used to dash to dtilt in melee with a few characters and it was brilliant, but that seems simply impossible to do with Sonic. You also seem to hold his neutral B in rather high esteem. From everything I've experienced, it just doesn't seem to be usable. The opponent can usually just punish me, whether in ground or air anytime I use neutral B.