(There's no video for developer.apple.com FTP Archive yet. Please contribute to MR and add a video now!)
Archived partial copy of files that were available on the ftp server at developer.apple.com, this contains SDK, developer tools and sample code files for developing for PowerPC classic Mac OS as well as very early versions of Mac OS X.
The archives themselves are extensive with around 138,000 items in the first one and 6000 in the second one, the downloads are ISO files which can be mounted or burned to Dual Layer DVD or imaged onto an USB stick.
You can search an index of the files included in the ISO images by downloading the Developer Archive Index files (which can be opened with Disk Tracker 2.x or later), before you decide to download one of the full ISO images which are pretty large.
Please let us know in chat if some of the files in those ISO should be made in a separate software page on here and feel free to do that if you have the time and knowledge to describe them.
A copy of FTP Archive #1 (HTML web pages and PDF documents only) is also preserved on ARCHIVE.ORG
Developer_Archive_Index.dtc.sit (1.74 MiB / 1.83 MB)
FTP Archive #1 searchable index / DiskTracker catalog, compressed w/ Stuffit
developer.apple.com.iso.zip (2011.17 MiB / 2108.86 MB)
FTP Archive #1 (HTML web pages and PDF documents only) / ISO image, zipped
developer-apple-com-v2.dtc.sit (66.94 KiB / 68.54 KB)
FTP Archive #2 (a.k.a. ftp.apple.com_v2.7z) searchable index / DiskTracker catalog, compressed w/ Stuffit
developer.apple.com-v2.iso.zip (4329.17 MiB / 4539.47 MB)
FTP Archive #2 (All files, prior to February 2008) / ISO image, zipped
informatimago_next.dmg (1994.76 MiB / 2091.65 MB)
Download of the next directory off mirror.informatimago.com providing legacy Apple documentation as well as links to stanford.edu and fu-berlin.de if they still work. / DMG image
Emulating this? It should run fine under: Basilisk II