You probably won't be able to sit through this movie, I wasn't. It's good for a laugh though.
This is the plot, from the part of the movie I was able to endure: There's basically a big solar flare, and it's somehow going to set the atmosphere on fire. The solution: We'll blow up the ocean! (I'm not making this up). The water thrown into the air will put out the burning atmosphere, or something.
The president is portrayed as naive for thinking that blowing up the ocean is too rash and/or stupid a move. Really, I'm with him on this one.
Also, meteorites are falling at cities for some reason. Fortunately shooting them with fighter-launched missiles makes them completely disappear.
Maybe they shouldn't have tried to make a serious movie based on a Homestar Runner cartoon. If you don't know what I'm talking about, check out this link: http://www.homestarrunner.com/cheatcommando.html