Sync course videos in iTunes U

Hi

I recently started using tutorials I iTunes U. There are some tutorials that are called "Course" which are optimized for iOS and there are others called "Collections".

I don't have any problems with the ones that are only available in course, but there are some courses ,also available as collection ( like "Introduction to Algorithms" ). I use course type to download the videos and PDFs with my Macbook but when they're downloaded, PDFs are available in course type and videos are available in collection. So I have 2 of the same tutorial and when I sync my iPad, when I choose videos in course, they start downloading.

Any opinion why this happens? Any solutions?