Yes, that’s reputedly Grant Gustin’s Barry Allen fighting the Reverse-Flash on the Vancouver set of the CW's The Flash Wednesday. We’ll let it sink in for a minute.
While it was teased in a blur of yellow lightning in the pilot episode of the series, it may come as a bit of a surprise to see Flash’s opposite-hued arch-nemesis come into the show this early. As they’ve already filmed the crossover episode with Arrow, due to be the 8th of the season, it’s safe to assume this is happening in 9 or 10 - putting it likely as the Fall finale just before the winter break of the series.
As to who is under the mask, watchers of the pilot likely have a couple of candidates in mind. Rick Cosnett plays Eddie Thawne on the series, after all (any facial recognition experts want to weigh on whether that's Cosnett?), but there’s also the mystery behind Barry’s mentor, and the possibility of another character who simply hasn’t been introduced yet. Check out the rest of the images of the fight from the set of the series, courtesy of the Grant Gustin Fan Site.