When I see this, I actually see a lot of potential for a movie. Now, granted, I've never played either Portal or Half-Life, so I don't know the world that Aperture Science is supposed to take place in, but that actually gives me a bit of a clearer head when considering this being a movie.
The way I see it working is, instead of having Aperture Science be some madman's magnum opus, have it be a legitimate research facility that specializes in giving scientists free reign to invent whatever they can, as long as it can "benefit" mankind. Now, since these inventions would need to be tested, they get various "volunteers" from across the world. Chell could be one such volunteer, possibly a lone wolf, no family, no friends, living her life as she pleases until one day a couple of guys kidnap her and take her away. At Aperture Science, she's forced to do testing with the Portal Gun in a vast facility where we can see others doing the same testing, but without the special boots to save them, so we would see various people brutally failing and being whisked away.
Now, if the producers really wanted to, we could even throw in a "love" interest in the form of Aperture Science wants to be self-sufficient in their test subjects, so they try to get the stronger ones to breed, introducing a male lead to compliment Chell. After a bit of time, we'd have this scene here happen, and they'd have to explain how she was able to find the Portal Gun and why it was there in the first place, but when we get to the end where she finds herself trapped, we could have the male lead get shot down and Chell whisked away back to her cell.
At this time, I'd have GLaDOS put into place, and instead of the instant kill-everyone-with-neurotoxin that presumably happens in the game, we'd see a slow transition from the human workers/guards we see in this vid to mostly robotic ones. Possibly starting with an engineer coming in with some guards and installing a new camera system, followed by cleaning robots that look like prototypes of Atlas and P-Body, and then having the food become less and less "natural" finishing with the hand that feeds her going from a human one to a robotic one. During this period, Chell is banned from testing, so she can only sit in her cell and watch the changes as things "improve" from the current dismal setting we see into the nigh-pristine setting of the games. After a while, the door to her cell opens, and as she slowly exits, she is presented with a new Portal Gun and the special boots and we finally hear GLaDOS. The next few minutes would play out much like the movie and have her proceed through Aperture Science, but along the way find not only the "Cake is a Lie" chambers, but also several gruesome, still bloodied chambers, while GLaDOS explains it away by quoting the common computer mantra of "humans are inefficient". The end would, again, mimic the game and have Chell defeat GLaDOS, with a snippet at the end of the credits teasing the second movie in the same way the trailers for the second game did.
TL;DR - Portal Movie is more than just fan hype, it could have the potential to be a blockbuster with the right plot