I think Amell's a little off base with his criticism of DC's movie slate announcement and the casting of Erza Miller as the movie Flash. I don't even think DC crafted a press release about that casting, nor was a big deal made of it. There was certainly no intention to upstage Gustin as the Flash, but if the film Flash had been cast, it would naturally be mentioned when the slate was announced to investors and the information would become known to the public. Very little about the casting as been said since then, if anything at all.
Also, he should have kept his mouth shut about his line of thinking that it's more difficult to produce a seasonal television show than it is to create a feature film. His argument could be countered swiftly and easily, and I certainly don't agree with him.
Much more time, energy and money goes into producing a feature film that is meant to be a franchise-starter or part of an over-arching series/universe. More often than not, the filmmakers and crew will spend roughly a year (or longer) to tell ONE story -- and so much is riding on that one story that they will often only have this one shot to get it right.
The serialized aspect of a TV series allows for much more time to tell an over-arching story featuring characters that have the oppotunity to be constantly evolving. Of course, I'm not claiming the 23-episodee production schedule is easy to manage. That wouldn't be true and we all know they probably work just as hard as a film crew does. However, the episodic nature of television allows room for continuous improvement. If they have a weak episode, they can hopefully bounce back next week or later on in the season. If something just isn't working, it can be retconned, modified, or completely removed as a season progresses. If the initial pilot episode isn't as strong as it should be, the producers can note the criticisms and work hard to make the show as good as it can be moving forward. Also, since shows like this are still writing and filming episodes as earlier episodes air, the writers/showrunners have the opporunity to listen to fan reactions. Remember how we were all complaining about Diggle not wearing a mask when he's in the field? Well, wouldn't ya know it, now he does!
In truth, he's comparing apples to organges. Yes, films have bigger budgets and they can put things on screen to TV shows just can't, but TV shows have more time and flexibility to tell stories, etc.
