That was cool, I was surprised we did not see the bat signal in the sky.

~Morpheus

Well...

I thought it was pretty cool..

Those look like birds.

Also, it makes it easier to understand how birds could be spooked by fireworks or something and all die. If they are used to roosting at night and not flying around like that, then they bump into things and each other, then they die by the thousands.

I say it's Starlings as mentioned in the OP. I don't live in Toronto, but where I live we see Starlings flying in massive flocks like this on a regular basis.
Pretty cool never the less.

Wow ...spectacular and it costed nothing to the new year's celebration organisation and to the city of toronto, i guess sometime natural entertainment is as good