I have also scalping experience, so I could occasionally "predict" the movements of a few assets (usually FX Pairs) correctly with the help of Technical Analysis. But remember, as my profit was a lost for the broker, soon the manipulation started. The options expired with a delay, so that an profitable trade became a losing one. Its funny how every delay made my previously profitable trade into a loser. I wrote to them and got no answer. I called, but was put on hold and didn't get any support at all. My profits were gone due to the manipulation trades.
So I decided to withdraw the left money, which took horribly long. I already gave up, as I couldn't get any helpful answer from the "Customer Support" (a huge joke, I think the guys sitting their have no clue about options). In the end I got my money, it wasn't a huge amount, so I wasn't freaking out about the long time waiting. But imagine waiting weeks to get a larger amount of money back, which you need. I was lucky that I opened my account with a small amount of money.
This is my experience with binary options. I haven't try the other BO brokers, but please people, be aware as the BO brokers are not regulated. If you are too profitable, they easily could take your profit. You can't sue them, nobody will help you.
I've just started to look into this as well (have been trading spot for about 3 years) and from what I have seen the possibility of manipulation is there from any broker who's charts / data does not go straight to market. There are many brokers out there who trade in house and therefore have a vested interest in helping you give them money. it's worth doing the research on the brokers who place your trades straight to market which eliminates manipulation