iMovie '11 will not import from Movies folder

iMovie '11 gives me an error saying that it cannot import a .mov or a .avi file from the Movies folder- that I do not have sufficient access privileges for operation. I recorded two time lapse videos from Gawker as .mov. When I tried to import that, it gave me the error above. So I went into Quicktime 7 (Pro) and exported them as a .avi file in the Movies folder. When I tried to import them as a .avi, it gave the error above- I don't have sufficient access privileges for operation. I want to combine two very short time lapse videos into one video. Is there a way to fix this?

On a similar note, I get this error when trying to import a .mov file from the Movies folder: