The way I understand it, what happened was that voice-talent unions felt that their agreements and pay was based on a certain degree of exposure. Internet streams opened their work to a larger audience than contracts were based on, and they felt they were due additional pay for the additional exposure.
It's similar to how department stores have to change their posters of models regularly because the model is only paid for x many days of exposure.
Personally I think it is a whole lot of hubub for pennies, but I can respect the thought behind it. If internet streams are to be successful, they need to be treated professionally and that includes paying for things.