So, what's happening when I watch a video on my PC that is feeding into the Roku tv via hdmi? Is Roku actually capturing info about the content of the stream,

So, what's happening when I watch a video on my PC that is feeding into the Roku tv via hdmi? Is Roku actually capturing info about the content of the stream, or just the fact that I'm streaming from the PC? I'm fairly sure they aren't so blatant as to grab screenshots, but are they doing some sort of analysis of the video stream directly? Just stuff I wonder about.