I have movies in mp4 format, which play in quicktime...and I wish to burn them to dvd (they are copies of DVDs I won, which is legal). The help book says that is the correct format to put them on my iPod, but I wish to burn them.

When I drag them to popcorn in the video section it says I do not have a valid "VIDEO_TS FOLDER"...what is this? And what format do I need to have my movies in to burn them to dvd.

Popcorn won't make your video DVD. There are two things that need to happen, neither of which Popcorn can do. One is to convert your videos to MPEG 2 format. The other is to "author" a VIDEO_TS folder. Toast does this but not Popcorn.

Typically when people want to copy a DVD they own they learn (elsewhere) how to remove its copy encryption and then have Popcorn burn the non-encrypted VIDEO_TS folder to disc. I suggest going that route rather than using the mp4 files that were created from the DVDs you won.