Here's a screenshot of a paused video you've all probably seen a dozen times, when a camera mounted on a runner in the marathon captures the first explosion. This particular location is at the UK's Guardian website, but the same runner-cam video is all over the place, like at Business Insider, and others.
On this particular version, the announcer is just saying, "...with the finishing line in sight, this footage, shot by one of the Boston Marathon runners, captures the moment of the first explosion...." You see the cloud of the explosion on the left. When you watch the video, you'll see that the runner is about two buildings down from where the explosion occurs, and you can see all the way down to the building where the explosion happens.
In the same Guardian video, immediately after this scene, we see this, another screenshot of a different video--a stationary one this time, paused:
See the cloud of the explosion on the right? As this video runs, the announcer is saying, "that moment again, as a steady flow of runners cross the line. There's confusion and panic. Ten seconds later, a second explosion...." You don't need to trust my transcription skills. Watch the video for yourself at the link above.
Another video, very familiar to all, shows the "moment of the explosion" from a higher perspective, as if from a building. You know it. It's the one where you see the older man who falls, but later we're told he gets up and finishes the race. Touching. That video's here, as well as lots of other places. And here's the still from that video:
In all three videos, we're supposed to be watching the same exact moment--the instant of the first explosion at the Marathon. It's first from one direction, then from the other, as you can tell by the way the runners are moving. Now, here's the rub. In the first pic and video (the runner-cam), look to the side of the street where the explosion is occurring (the left of the frame). We see the curb, with metal gate-like structures and spectators crowding up to them.
In the second and third views, look at the side where the explosion occurs (now the right of the frames). See all the blue banners on the gates? See all the brightly colored, very visible flags lining the side of the street? Now wait just a cotton-pickin' minute! How the hell did those get there?
These are clearly two different events. The same street at the same moment can't have plain metal gates and people AND brightly bedecked, corporate sponsored banner covered gates and dozens of international flags. It just can't be. So why do you suppose we're being told (from the left, right and center) that these are all footage of the "Boston Marathon Bombing?" And if one IS genuine footage, and one is NOT, then just when did another explosion occur in a very similar looking building as a whole bunch of runners went by it? And why would someone make video of it and say it's the infamous bombing? Why, indeed.
I smell a number of rats.