Besides the flickering, that looks great. I have some suggestions that will fix it...but it WILL increase render time, by a lot. With MR every scene is different. so its hard to say what it is. but these setting should fix it, although it might be a bit overkill. First of all, change your samples under the MR render globals to either 0 for min and 2 for max, or even better 1 for min and 3 for max. Also use the Mitchel filter. It creates the best image. Now... Change your FG points from 1000 to at least 2400 for a final render... I know. it will take a lot longer.. If I were working on a big project at a studio, that had a lot more frames, I would go thru and really take apart the scene/settings to optimise the render time and the quality of the image. but in this type of situation where I would just increase the settings accross the board, quick and easy, but just takes a while to render. I guess it depends on if you want to take time to work it out yourself, or just let the machine chomp away. I hope it works, if not let me know.
THanks!!

Brian