This specific file is the of a compressed archive. It doesn't contain the whole movie; instead, it holds a specific "slice" of the data. You need every single part (from part01 to the final number) in the same folder to successfully watch the film. Common Issues & How to Fix Them
Delete part29 and re-download only that specific file. You do not need to re-download the entire movie.
Never move part29 into a separate folder until the extraction is 100% complete.