OF COURSE Dota has a metagame, silly. A very indepth one at that. I don't think you should be making video series on these games if you don't even understand basic terms like that. What would even lead you to believe that dota doesn't have a metagame? Sheesh, some people...
Anyway, trilanes are a trend. Look back a couple of months, or even towards the International, and you'll see different lanes, different heroes and different strategies, all within the same patch cycle. Hell, in the previous patch, dual mid lanes were actually reasonably popular (Morphling/CM or Kunkka/SD).
What was the point of this thread again?