A good chunk of sports car series put their races on Youtube. I usually spend the winter watching series I don't spend much time on during the season. Right now I'm catching up on SuperGT, after that I will probably move on to British GT.
Has replays of pretty much every racing series you can think of.
As far as stuff to watch over the winter, the only things I can think of off the top of my head are Formula E, and then starting in January, the Toyota Racing Series from New Zealand. There's also an ice racing series in Scandinavia.
This is definitely the driest part of the year. Nothing major starts happening until things like Daytona, Bathurst, etc.
Has replays of pretty much every racing series you can think of.
As far as stuff to watch over the winter, the only things I can think of off the top of my head are Formula E, and then starting in January, the Toyota Racing Series from New Zealand. There's also an ice racing series in Scandinavia.