Sorry, but we will need a lot more information to work with: What Magix program and version are you using? What kind of video clips are you intending to import (video file format/codec, origin)? How do you go about this import process? What does it mean when you say you're trying to "get video clips from PICASA"?

Generally, I can only say that whatever program you're using you should:

1.) Make sure that the files you're trying to import are even supported by it. Check the documentation for supported file formats.
2.) Identify the actual physical folder on your hard drive where Picasa is storing the files in question. Make sure to get the files from that folder. Just knowing that the files are "in" Picasa won't help. You need to know where they are on your hard drive.