Having followed this theory with interest over the years, it was a pleasant surprise to channel hop onto this interesting wee documentary.
Informative, without bias and exciting to watch (if sci-fi excites you like that...). It's funny to think that life from outer space could, quite possibly, have already landed, when there are still many who don't believe that life outside of our World exists (past the big fella' upstairs).
The panspermia theory is well explained here, and features the basis of the argument with both sides presented well. Lay back, watch it with an open mind and you'll come out feeling a little more informed.