Personally, I don't have time to play with these things and check server seed hashes before and every roll, but you have good point that such things is difficult to prove. But I think that if someone from this forum with good reputation would record such video, there would be no reasons not believe him. But now we just have some talk without any solid proofs.
That's already been done by several people in the scam accusations forum and has spanned multiple years between posts which shows the practice is still current and never ceased. Like I said before, NO ONE can "show solid proof" and those that give this statement, like I said, are ones who dont actually save anything themselves or they would have noticed it. It took about 14000 rolls before I saw it twice with my own account. When TheQuack decided to ban it because he finally noticed I had a bot RECORDING it all 24/7 365 (it was up to about 29K rolls), it was to late. I'd already seen the manipulation multiple times myself. Not to mention the other 596 accounts I had access to for 3 full years, I saw it very often. But also like I said, it was for free rolls, I dont really care of those are manipulated or not. It was the dice rolls that mattered and over the millions of rolls I recorded, I saw no manipulation.