Download from WebTech won't open / downloads as “ROBO-SENSEI.sea.txt” (Mac)

Hold down the "control" button while clicking on the icon.
From the menu that pops up, select "Get Info".
In the box that pops up, look for the section called "Name & Extension" (If all you see is an arrow and "Name & Extension", without a box with the name of the file, then click the arrow to the left of "Name & Extension").
The box below "Name & Extension" should read, "ROBO-SENSEI.sea.txt" - you want to delete the ".txt" from the end so that the name reads, "ROBO-SENSEI.sea".
You will be prompted with a warning about changing the file's extension. Don't worry - we want to do this. So, when that box pops up, make sure and click the button that says "Use .sea".
Below the "Name & Extension" section, you will find "Open with:" (as with the "Name & Extension" section, if you only see the header and now drop down menu or button, click the arrow to the left of "Open with:")
If "StuffIt Expander" is not the application chosen, click the drop-down menu to select it. If it is not in that list of options, click "Other..." and select it from your Applications folder. If you do not have a copy of StuffIt Expander on your computer, go to the following link to download a free copy. http://www.stuffit.com/mac/expander/download3.html
Close the window, and then double click on the file now named "ROBO-SENSEI.sea". StuffIt expander should load, uncompress the package, and leave a folder with the name "Robo-Sensei(Mac)".