Honestly, the porn industry was always making large sums of money in this type of field, so perhaps Youtube was a little short-sighted. For a more general statement, they started the lawsuits when it became economically viable to, i.e. the companies using the "infringing" patented methods made enough money to sue for / strike a license deal.
There's lots of streaming video on the web. For trolls, plenty of targets. Millions of potential defendants. If they issue 100,000 threats to sue, there will be at least a few that decide they'd rather pay than fight. Which then enables the troll to repeat the process.
If you had just watched an episode of The Jetsons and then were presented with a global communications network attached to computers with video screens, live video communications would be about the first thing you would think of. If you had also watched some adverts during the episode however, you would probably come up with live video porn, and maybe Amazon.