who attacked the runners in Boston?

WSJ posted a video showing two male persons with backpacks and caps walking in the crowd.

but i find this video absolutely bogus - http://www.marketwatch.com/story/fbi-releases-photos-of-2-boston-marathon-suspects-2013-04-18-181031032?dist=tcountdown

i don't see them putting their begs down and i don't see the video of the guy in white cap walking away from the scene without his bag. nor do i see any suspicious behavior - they walk the same way everybody else does. i see lots of people with bags and caps. there is really nothing in this video that could suggest these 2 people are involved. 

but here's what i think. judging by the explosion i'd say these were not terrorist attacks in the strict sense. a real bomber would get a coke can full of gun powder (which is not hard to get in the US. u simply disassemble a few shotgun rounds), strap it with nails and bolts and place them for maximum casualties. yet on the video we see: weak explosion (with all my regards to the victims but the explosion was very weak), we see white smoke - indicator that white phosphorous could have been used, and we see more than one explosion. so first conclusion - it's not a job of one man. second conclusion - it's not a job of the so called "international terrorists", and third - the insides of the bomb could indicate military background! 

this was not a terrorist attack but a reminder to the US people. and the US people should finally begin to THINK instead of act on emotions. international terrorists did not attack WTC - the US government did. it was a controlled demolition and only the blind can't see it. watch this video where the US engineers say "9-11 was a controlled demolition" over and over. not a single engineer said planes could have damaged WTC to the extent of their collapse. watch it!

the Boston act was not aimed at getting maximum people killed. this is obvious. and why would terrorists attack a sport event when they can do much more damage in a subway?... they didn't want to do much damage that's the issue here. this is the frightening act. and i won't be surprised if they find Iranians behind it...