Broken bottom bracket? Pedals are pretty loose Unlike the rest of the broken bottom bracket questions, my bottom bracket does not make any noise or feel like anything is grinding. 

There is about 1/2cm of play left to right that i can see on the top chainring. I can definitely feel it being loose. 

What is the worst amount of damage that I can do to my bike riding like this? (assuming that I dont fall off and die etc because of this little matter)

The bracket itself is new(ish) it was installed there about a year ago, but I did ride 50 miles per week on it since. 

What could have caused this to happen? My best guess right now is that someone did this to my bike because I park it out doors while I am at work.  

edit: 
My level of expertise in that area of the bike is pretty low, so here is a video of what is happening:


                
            

(set quality to HD)

I noticed that on the side of my chainrings there is a noticeable gap between the seal and the bottom bracket. 

So what is going on here?  and more importantly can I fix it myself without special tools

Can I expect any kind of a warranty from the bike shop who put this in a year ago ?

Solved:
Took out the bottom bracket.  It is fine and so are the cranks. The threads on the frame are not fine though. I need a new frame :P
Here's a quick test. Grab the crank arm that you say is moving and wiggle it. Does the arm on the other side move? If so, you've probably got a bottom bracket problem. The answer then depends on whether you have a sealed or loose bearing botton bracket. As mentioned previously, a sealed shouldn't do this after 2600 miles. (Neither should a loose bearing, but it is more likely).

If the other arm is not moving, then the one wiggling is probably coming off of the bottom bracket spindle (the axle). The spindle may be rounded off, or the crank arm may be rounded off. The only way to really tell is to take it off and see. This probably means that it wasn't installed securely in the first place.