If you just have a list of filenames for 17–28 source files:

The source files are the raw Adobe Animate project files used by the crew to create episodes 17 through 28. Unlike the final rendered video on YouTube, these files contain:

The "source files" typically refer to the project files, which contain the raw vector assets, tweening data, audio tracks, and action scripts used to produce the final video exports. These files are critical for archival, remastering, and asset extraction.

The files showed how complex scenes, like the elimination ceremonies (Cake at Stake), were structured and animated. Availability and Removal

To fully appreciate the 17-28 band, see how it fits into the broader BFB continuum: