There are various beta launchers currently going around to play the offline Starcraft 2 beta maps. At this point in time the most stable and trusted is the LazyTown Lancher v2.
Use discretion when using any other beta launcher. The only files you should ever have to replace in your Starcraft 2 folder, is the Base.SC2Data file for AI play. This file is the AI file. Check for the most recent AI release here. I recommend staying away from any other "AI mods" that have other file modifications. Just be patient and the next AI mod will be released.
Be cautious of fakes, and stay away from anything that asks you to modify more than the Base.SC2Data file, especially if someone that uses your SC2 for online play, as this is the perfect opportunity for key loggers to sneak in.
If you are unsure, just stick to the tried and true. Use LazyTown Launcher 2 and select a Map. It's that simple.
I repeat, if a Beta Launcher doesn't work, stick to just using the LazyTown Launcher