Practice =/= Flash movie
This is the kind of thing I would do to practice and learn how to animate better, and it is definitely an important thing to do. However, there is a reason why things like this shouldn't be submitted, imagine every user made little practice movies and submitted them here. The portal would be flooded with thousands of 15 second movies with no substance, perhaps things that aren't animated horribly, but things that we don't need to see here. Consider making more "feature length" flashes or at least something with more substance than a line flying around the screen, and keep things like this to yourself (but don't stop practicing of course)
As for the animation, your frame rate is either slow or you just drew it very jumpily. it could be smoother, but at least you are putting effort into frame by frame animation. Keep in mind that animating a line is even more simplistic than animating a stick figure, I can't really throw up my arms and say "YOU ARE AN AMAZING ANIMATOR, MAKE A REAL MOVIE NOW!" because real movies involve more elaborate shapes and drawings.
I hope you take the time to practice such things and then apply them to a real movie, something that I can show actua appreciation for.