As valuable as you make it.

That question reminds me of how television and movies were used in the classroom in the nineties.  When I was in school, high school and college too, teachers would try to find a movie on the topic of a subject we were studying in class.  They would play the movie during class time, uninterrupted and encourage us to take notes (which we never did) to talk about at the end of the movie (which was usually three days later).  This can be valuable if you start and stop the movie for thoughtful discussions, and not have a video babysit the students.

Same goes for websites. Providing students a web address to go to without any purspose or directions becomes a newer version of technology babysitting our students.