All in all...it's gonna happen. People copy other people...whether they like it or not. If you get two people that play the same character....and they know each other, you're going to get pieces of styles that they copied. Whether it was intentional or not.
Ken didn't care about Videos because it doesn't show exactly what a player can do. HOWEVER, Ken did care about training other people because he said he was afraid of them learning his style. (He mentioned so himself in some interview he had.) M2K doesn't mind playing other people repeatedly...giving them advice, etc. However...maybe he minds on the video thing? Is there any difference? Not really...both have a silly fear that the other didn't mind.
I digress- People look for something good out of another player's style and then incorporate it into their own. It's going to happen. The statement about the original always being better isn't true. That'd be like saying a son could never surpass his father in something they both do. That...just isn't true. It should be that the original is USUALLY better. It was also, said however...that being able to PROPERLY utilize it is a different story.
Another example (I don't care if it's an anime...it still applies): In Prince of Tennis Ryoma comes back one day to hear that a kid is copying his style and beating people with it. I mean...he copied right down to the tee...motion and everything. Takes him by shock a little. Then he realizes...it's just not the same...he doesn't know the proper application of it. Also...he doesn't have the proper experience, understanding or training to be good. The kid gets soundly beat by him.
I've seen it already, myself. I've got friends of mine that see a character I use...think I only win because they're cheap and then tries to use that character. They'll get some practice in without me knowing, and then pull the character out to show off a bit. I'll give a perfect example...DoA4 and Christie. Now I don't play the game...I had probably played it 3 times prior. I was just racking up victories. They spend a couple weeks training, and my one friend is SO confident. Bragging that I can't beat him because he has Christie. He loses and I'm still waiting for it. When he picks Christie...I PURPOSEFULLY pick my secondary, Elliot. I soundly beat him. Then I pick another character I'm not too familiar with, Li feng...and win again. I told him once, and tell him again...."Just because you know the character, and copy what I do....doesn't mean you'll win." Then he challenges me to a Christie ditto...RAAAAAAPE. Then I leave the Christie out just to let it rub in a bit.
If you know your character well enough...and know your own playing style...you can't lose to it. There's really nothing to worry about.