They stated that the content in the video was only a few weeks old, and that not much would have even changed after those few weeks passed and they did a re-recording of that area of the game. I personally think it looks pretty good.
However, I definitely agree about the voice acting. I know they've already stated that they aren't too worried about the grunts because they don't want players empathizing with them, which kind of makes sense. But in my opinion, the problem here is consistency. The original trailer video had some pretty decent voice acting. Whoever voiced Barney did a commendable job, and the few scientists in the trailer were also voiced pretty well. Then we have the grunts. The dialog isn't that important, but the way they're voiced really comes off awkward and just sounds plain silly. It was funny, I'll give them that. Hearing one of the grunts go "Oh yeah. He'll definitely pay." then get blown the fuck up by a satchel charge is actually pretty priceless. Still, they could easily spend some more time with that little scene just to make it play out a bit smoother. Keep the same, cheesy dialog (because that's part of the humor), just work on the voices so they don't sound completely awkward.
And the last thing I wanted to point out regarding content was the song at 2 minutes in during the big firefight. It just...didn't fit too well with the setting and situation in my opinion. It sounded way too trancey for Half Life. I know the mod is more like a "re-imagining" of the first game, but the song just doesn't fit. It might sync well with the scene, but the "sound" needs to suit the setting and atmosphere a bit better.
I honestly think they should just release the 1080p version so we can get a better idea of the visuals. The so called "damage" is already done, though I don't think this media leak should be a huge deal anyway. Self-proclaimed fans still would have found something to bitch about even if the BMS team released the video when they had originally planned to.
No one should be expecting this mod to be on par with a triple-A commercial title; and I don't mean that in any negative way towards the BMS team. This mod looks great and will at the very least be an enjoyable trip down memory lane. In other words, worth playing and worth the time and effort that the team put in to it.
PS: Thanks for finding another upload of the video, Srred.