Modify a FLV file so the keyframes are not so far apart?

I download a lot of FLVs to edit and often the keyframes are 10 to 12 seconds apart, which makes it very difficult to do lossless keyframe editing without losing scenes that I want to keep. Worse, often the keyframes don't change when the scene changes, they just seem to change every 10 to 12 seconds regardless of whether the scene has changed or not.

How can i convert these FLVs to a format where the keyframes are much closer together so that I can edit more precisely? And is there a way to do this losslessly, without degrading the video's quality? Thanks.