You just never know and you should always be careful when looking at videos. Case in point: I purchased a horse a few years ago. I rode her first and could tell that she was naturally a little bit "hot" although I felt like I had control all the time.
The woman I bought her from showed me youtube videos that the person she bought it from had given her. The videos did not sway my decision to buy (the price did), but they *did* sway the seller to purchase the horse several months before. She decided to sell the horse as it wasn't getting much use, etc. etc.
Well I bought the horse and after uncovering some issues I started doing some homework. Found out the horse had traded hands several times in a year...found the last owner I could find and found out this horse had a very horrible history of abuse and had been confiscated by animal control. She'd had the horse for years and spent a lot of time rehabbing this poor thing. The horse had never been in a horse show.
So that brings us back to the videos. Well this horse was a day bay with no markings. I bet if you comb Youtube long enough you can find plenty of videos with plain bay horses with no markings. All the better if the video quality isn't the best. Upon closer inspecting and after knowing the horse better I could tell it wasn't the same horse...but wouldn't have noticed right off the bat.
My point here is that videos are only worth so much. Especially if you don't know that it's the exact same horse or what kind of sedatives the horse has been given prior to the video. Just too many variables.
This is a horrible thing you've been through and I'm sorry. My advice would be to cut your losses and see if you can sell the horse even if you basically have to give it away. If you're willing to send it to a trainer that's good, but still risky as you don't know if the horse will ever be "beginner friendly." Some horses are not, no matter how much riding and training they have.
Sorry to hear this. I hate knowing there are people like this out there who will lie and cheat to make a sale.