Most content falls under “fair use” for preservation. However, Toei occasionally issues takedowns. To respect IP:
Because Shaider is a classic "Tokusatsu" (special effects) program from the 80s, official physical copies can be difficult to find outside of Japan. The Internet Archive allows researchers and fans to: shaider internet archive
Once you locate a page with files, you can download them for offline viewing: Most content falls under “fair use” for preservation