The bike in that video has only one speed and is a fixed gear. You won't be able to do that on either of the bikes you are looking at.
Generally, more "speeds" means that you will have a wider range of gears to choose from to be efficient in the terrain that you are riding. As a note, the quality of bikes at Wal-Mart is usually not the highest. If you plan on doing serious trail riding or BMX-style jumps and tricks, you will likely break the poor thing relatively quickly.