I'm gonna say, very probably not. I don't have the video right now - I'd swear I was looking out for it, but I must've forgotten - but there's a few things that suggest it's not her. Although strange things can happen with AV, and I can certainly see the resemblance. Anyway, in no particular order:
1. I can't find many pics of Mai, but while she does have a mole in about the same spot, it seems to be much lighter than Miku's.
2. Googling their names together - in kanji, of course - doesn't seem to produce anything interesting. If this were a thing, I'd think there would be talk about it, especially since-
3. Miku is still releasing videos. So if she's started doing AV too, she's somehow been really sneaky about it, while still looking like herself.
I was going to say she's still underage too, but her wiki page says she's 19 now, so that's not a problem.
Once again, it doesn't look likely, but my Japanese isn't so strong, and my resources are limited, so I could be wrong either way.
Thanks for the post though. You've certainly sparked my interest in Mai now. She looks really cute, and the reviews on her video look pretty good!
