First impression last. I am sure that they already did stupid mistakes. It is just that they do wanna impress viewers or may be afraid of being the reason to avoid. Besides the trader might want to look believable. Well how would you gonna look real if you can only show is those silly mistakes of yours right? And I don't find any fault with that even in some businesses usually happen something like this.
Of course they do that, what else would you expect especially when they are also selling signals and claiming to be selling you expensive information and professional advice? I've seen so many paid channels, and years ago stupid enough to even pay for premium and it's all the same bullshit.
Same thing with gamblers who only show good tips, it's all worthless.
The only honest ones are the ones who don't ask for payment I think. But even those give up and disappear when they do so badly.