Birds of prey can be very difficult to identify at long range. Different species can take on different flight characteristics and appear to be something other than what they actually are. In this case I think the two alternatives would be Bald Eagle and Rough-legged Hawk; both are large and can be completely dark like a TV. At this time of year they are both much more common in Ontario than Turkey Vultures, even Golden Eagles are more numerous than TVs. That said, your bird could very well have been a vulture... a very cold vulture.
Iain