I'll bite, even though I'm somewhere in-between unschooler and relaxed homeschooler.
We do not limit screen time except for a 5-6 hour period each day (weekends and when I or DD is sick are excepted). Parenting-wise, we are pretty heavily RU.
We do not own a TV. We were given one as a gift about 7 years ago and it sat around getting dusty for years before we gave it away. No one in our family really likes TV, but DH and DD sometimes watch videos.
DD (age 6) is allowed to watch whatever videos she likes (within reason, nothing really gory, extremely violent or sexual) on Netflix instant watch, Hulu.com, Youtube.com, etc. Every now and then she decides she would like to watch a certain TV series on Hulu.com and she watches a fair bit of Youtube videos (maybe 1/2 hour a day). When she does find a series of videos she wants to watch, sometimes she will sit and watch them for several hours a day until she's seen all of the episodes. That happens once or twice a year.
For our family, video or TV watching is not a big deal. None of us find the video format especially stimulating and prefer more interactive entertainment (video games and reading, for example).
Right now -- because of a temporary situation -- DD plays a particular online video game for several hours most days. I don't mind, because it is currently her only way to socialize with other children on a regular basis, and because she went from slowly sounding out 3-letter words to reading fluently at a 2nd to 3rd grade level by playing this game heavily over the summer. She really got into reading out of a desire to chat with the other kids and now she consumes books like crazy.
Other than that, we watch the occasional movie or documentary. We're pretty lenient about what she can watch but in general she chooses age-appropriate video, or close enough... in other words, she doesn't want to watch R-rated movies but we're okay with The Simpsons or Futurama.