Respectfully, I'm not at all convinced that green screening is the best way to achiev this effect. Ot at least I wouldn;t even try to green screen it. It's a rotoscoping exercise pure and simple. My reasoning is that you want the skater on top of the actual background he is skating on. You are not changing what is behind him. Also, trying to get a skater to perform those tricks on a green screened backdrop is just asking too much. Grindsing the skteboard on any green screen backdrop would rip it to shreds.

However, even though it is a rotoscoping exercise (in my opinion) it's not a nasty one. your mask only needs to be pixel accurate where two instances of the skater overlap. Also, there are good techniques to make the job less painless as well.

Just my 2p

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