Ad revenue from streaming video, the very category writers just struck for three months over, will be worth $6.6 billion in 2012, according to new research by Parks Associates. The firm estimates the same category was worth $1.4 billion in 2007. The reason these numbers are higher than others we’ve seen is partially because they include display advertising shown around videos, not just ads inserted into video streams.

“The bottom line is this market is growing fast and will be a significant source of revenue for the network operators,” said Parks Associates analyst Harry Wang.

Parks Associates said ad spending on all multimedia platforms, including mobile and IPTV VOD, will be worth $12.6 billion in 2012, up from $1.8 billion in 2007.

Just FYI, if you want to include paid online video and exclude mobile and IPTV, Parks Associates has a different estimate for you (from a different analyst at the firm): $11.3 billion in total revenue for online video in 2012, up from $2.8 billion in 2008.

I’m not sure if writers should feel good or bad about finally striking a deal to get 2 percent of this multi-billion-dollar space in 2010-2011. On the one hand, a small portion of a large amount is still a lot. On the other — clearly the AMPTP generates revenue in online video — even if this estimate’s 50 percent off we’re still talking multiple billions of dollars. Multiple billions the writers won’t see.