I bought Izzy from video. The seller sent me two or three videos of her at shows (showing in rail classes) and then sent me a current video of her free longing in their arena (she had been out of work for 6 months at that point). I am happy with her; she was more or less what I was prepared for.
I am also in the process of having a horse vetted for a customer that we have only seen via video. In this case I had a forum aquaintance video him for me so that I knew the video wasn't just showing the good stuff.
In both the above cases, the video wasn't edited, and were situations where the seller couldn't micromanage the setting.
I will let you know how the second horse goes if he passes the vet!
A third horse I bought off video didn't work so well. In this case the video was short clips of him taken and edited by the owner. The real issue with that horse though wasn't his performance/training, but that the vet doing the PPE missed that he had club feet...
I have bought nightmares and dreams off videos and even pictures! I have also bought both nightmares and dreams in person. I guess I just like to take chances! My current horse was bought off a picture, and I loff him! I also met one of my best friends by buying her horse, many states and miles away, off a picture.