Hello, and thanks in advance for taking the time to look at this question.
I'm questioning the legality of editing a copyrighted video and changing the audio track to something else -- mainly, making a comedy out of serious TV show by changing the audio track so that the actors seem to say things that are funny, rather than the serious things they said in the actual show.
From what I understand from doing my own research, it would be illegal to use old TV shows without the permission of the copyright holder. I wonder about it though, because I see things like this on YouTube all the time and they don't seem to be getting taken down. Why might this be? Is there a way that this falls under fair use as a parody? Is there some duration of video clip that is legal to use?
Also, is there a time limit on how long a video might be protected? From what I've read, US Copyright extends for 70 years after the death of the author -- which would mean that almost all videos would be subject to this.
I'm interested in creating some comedic parody like this, but I want to make sure it's actually legal and isn't going to get me sued.
Thanks again.

