I once ordered a Pioneer Beyblade VHS tape that has music videos playing during the previews, but I was disappointed to learn that there was a blank VHS tape inside instead of the real deal. I didn't bother playing it because I was worried that I might come across a horror movie, recorded disturbing footage, or porn, but now that I'm thinking about it, maybe it might be something extremely rare and interesting inside of the blank tape.
I had that happen once too, I bought a movie from Ebay and was dissapointed to find out it was a home recorded tape inside the box, so I had to buy another copy of the movie, I threw that home-recorded tape away but now i'm wondering if there was something rare on it.