I'll be shooting a video of a small parade that is going to last about 30 to 40 minutes. I know the D7000 can only shoot 20 minute segments, but I'm not sure what that means in practice. Will it just click off after 20 minutes? Will I then be able to turn video back on and keep going using another file or must I wait some period before it works again? Would I be smarter to work in smaller segments? Also, should I worry about the battery? Thanks for your help.