Pinterest has never provided a save option for video, on any platform. Images can at least be right-clicked in a browser, even if that gives you a downscaled copy. Video has nothing — no download button, no share-to-files, no long-press option. The only alternative to a tool like this is screen recording, which captures at your screen resolution, includes your own interface, and re-encodes the video a second time.
The distinction between video pins and idea pins is worth understanding, because they are genuinely different formats and people conflate them constantly. A video pin is a single clip stored as one MP4. An idea pin is a multi-page format closer to a story: it can hold several pages, each with its own image or video clip, plus its own text overlay. Pasting an idea pin here returns every page separately rather than only the cover, which is what tools that assume a single video will give you.
Pinterest stores video as ordinary MP4 with H.264 video and AAC audio, and importantly keeps the sound inside the same file. That is a real convenience compared with Reddit, where DASH splits audio into a separate stream and a naive download gives you a silent clip. Nothing needs merging here, so a Pinterest video plays with sound immediately.
One quirk that catches people out: Pinterest runs dozens of country domains — pinterest.co.uk, pinterest.de, pinterest.com.au and many more — and a pin shared from one country often carries that domain rather than pinterest.com. They all serve identical content, so any of them can be pasted. The pin.it short links produced by the mobile share sheet resolve too.