OK Photoshop et al. are all going to have you working on single frames, what you need is a VIDEO clone tool.
I searched high and low for some such beast to edit out dreaded 'Black Spots' from an unrepeatable video shoot in Belize last year where we had whale sharks coming verically out of deep water and hitting the surface chasing snapper spawn.
See post at LAFCPUG http://www.lafcpug.org/phorum/read.php?f=1...776#reply_95776
I eventually bought CHV's clone tool see http://www.chv-plugins.com/collclonepaint.html
I whinged a bit (being a Pomm with an Aussie passport) about having to buy the whole 'clone and paint' set of plugins because I'm such a cheapskate, but eventually I forked out a whopping US$49 (yes!) and believe me this tool alone is worth it.
You can key frame source and target areas, change size and shape of capture and target areas, feather the edges, blur the outcome etc etc - sure you can even do frame by frame, but where there are whole seconds of your 'spot in the blue' well - no need to key frame etc.
This is a very versatile tool and should be part of every adventure diver's post production suite.
If you are still trying to do all this stuff in Windows (which I was until last year!) I can only say I love my G5 Quad and Final Cut Studio, and I ain't EVER looking back 