If you watch “Battlestar Galactica,” you know it’s one of the best shows on television. If you don’t watch… get with it. The fourth season begins Friday on Sci-Fi Channel at 10 p.m. It’s not too late, and catching it up is easy. Check out “What The Frak Is Going On?,” a funny, fab recap of the first three seasons in eight minutes. EW.com also has a neat Cheat Sheet.