First find a TikTok or IG Reel you want to repost. Hit the three dots on the right and select copy the link. Then use your favorite app to remove the TikTok Watermark. I like to use SaveTok. Next head to Pinterest, click the plus(+) button on the bottom of the page, and select create story pin. Upload your video, fill out the info on the next page, add tags and click publish.